Digital voice or VOIP - which one to choose?

I am facing a dilemma that I am sure many others have faced due to the demise of the analog telephone line in the UK. I am dealing with an elderly parents phone line and I want to e sure that everything is covered and not too complicated for my parent to use. The local authority will be moving the Telecare service to one that has a mobile SIM and connects to a mobile network so that should be sorted hopefully.

However, there is also the landline and broadband contract which is coming to its end in a few weeks. I had intended to just install a VOIP ATA box and plug the existing DECT phone into it. However, I have had an ATA and VOIP facility for some time already myself and have had a lot of problems with navigating menu systems on the remote end that will simply not respond to any button presses despite various tweaks being suggested by the very helpful VOIP provider. On the other hand, a VOIP program on the PC works without issue, which means that the problem is definitely down to the ATA. Obviously I cannot leave my elderly parent in such a situation where she is unable to select the menu options when she calls the GP practice or the local authority or anyone else. The ATA solution is just too unreliable. Mum has never used a computer either so a software solution would also be a non starter.

The existing BB provider does no longer provides a contract with a landline facility, which means that she will need to switch to Digtal Voice with their partner company (BT - now EE) - or else to a VOIP provider. The issues are these:

a) BT/EE digital voice - convenient - just plug in the existing DECT phone that mum is familiar with to the EE router, but poor reviews for EE support, but I don't like the fact that its a proprietary technology that locks you into their router etc

b) VOIP - open technology with options and should work fine when using a VOIP/SIP phone, but Yealink handsets don't come cheap and I have yet to find any alternatives. I have no experience with them and am unsure whether they have accessibility features like amplification for example?

Consequently I am not sure at the moment which option to choose.

So my questions are these:

a) are people generally happy with "digital voice" and is it reliable?

b) does anyone have experience of the Yealink handsets and are there any alternatives?

c) the Telcare should have its own battery I think, but given that we will loose the ability for the phone handset to be powered from the telephone line, should I get battery backup for the router and any handset base?

I would appreciate any comments.

The only (initial) problem I had upgrading from a fibre/copper and analogue phone (DECT) to full fibre from Vodafone was a simple connector issue.

My original telephone system used the old BT master socket system and my wired phone system just plugged in. When the new Fibre/VoIP Router turned up I simply plugged my RJ45 network cable in.

The telephone transition needed an RJ11 connection from the back of my router to a free BT connector and I had one but it didn't work. The supplied RJ11/RJ11 didn't match anything I had and the installers cleared off before I found out. Turned out, while my old system used an RJ11 pins 2&5 to BT the router/modem RJ11 telephone socket used 3&4 both ends. My solution was to update to an RJ11 Euro panel socket hard wired on to my home wiring making for a tidy solution.

My telephone works exactly as before, any configuration happened at their end. Caller ID works as before but, as you might see from my other post today, my DECT Answerphone doesn't recognise the 400Hz caller hang up tone expecting instead the long established line current break to signal caller hang. My expensive DECT Answerphone is now stuffed by blind progress.

The thing is, one would expect anyone providing a new VoIP system to seamlessly replace a hundred year old system would both understand how the old system worked and make bloody sure his new one worked the same but no.

I think I may have solved the problem with DTMF not being passed. My SPA112 has the "DTMF Tx Method" set to "InBand". Having read up a bit more on the subject and seeing that `DTMF Process INFO` and `DTMF process AVT` are both set to `On`' I simply tried the INFO, AVT and INFO+AVT methods. Switching to INFO didn't do anything, but switching to AVT actually worked as did INFO+AVT, so it seems that the AVT method is the one needed. I can now press the 1,2,3 or whatever whatever button and the remote menu system now responds as it should do.

The curious thing is that A&A advice setting to "InBand". So what does this actually mean? And why didn't it work? Does the DTMF method depend on the handset or the VOIP provider?

BTW, I have also learned that the SPA112 has a major vulnerability with a CVT of 9.0, so I might be replacing this with a Grandstream. My SPA112 is behind the router although I do have a port re-direction rule set up for port 5060 to bypass NAT. I don't think this puts my SPA112 at risk because the vulnerability affects the management portal which cannot be reached from the outside.

If the Grandstream works OK, then I will try it at my parent's house for a while to see how it goes. Its much cheaper than spending 200GBP for a VOIP base and a couple of handsets. If I run into trouble then I will consider the handsets. I realise this is a bit of a U-turn, but if the problem I had with the ATA can be fixed by changing a setting, then I am beginning to think that I might have been a little mis-lead about ATA's?

Talktalk supplied us with a Grand stream ATA, plugged our old Panny Dect phone into it and it seemed to work fine. After porting to A&A tried to reconfigure the ATA, but no luck, it wouldn't respond to ***, not sure if TT have it locked down, or there's some other reason like being older Dect phone, so if your house phone can reconfigure the ATA be prepared to use that phone to reconfigure for your parents line.

Rather than using the existing ATA with DV or a VOIP provider, I'd very much recommend getting a VOIP capable DECT basestation and either using the existing handsets or getting new handsets as well.

I've used a Gigaset N300A IP based setup for around 10 years and it outperforms ATAs for call clarity and lack of echo as there's no need for 2 wire/4 wire conversion. It's no longer made but Gigaset have the N610IP and Yealink have alternatives.

In reply to a post by ferretuk:

Rather than using the existing ATA with DV or a VOIP provider, I'd very much recommend getting a VOIP capable DECT basestation and either using the existing handsets or getting new handsets as well.

Thank you for your post.

I was advised that elsewhere as well although I wasn't sure if it was a sales drive, so its interesting to hear it again independently here. VOIP base stations and handsets are very expensive. Not sure why that is, but an ordinary DECT phone with 3 handsets would cost me around 70-80GBP but a VOIP base and TWO handsets would cost close to 200GBP. A third handset would cost another 70GBP. The cost difference is not trivial. Before I spend that kind of money - and this even before considering a replacement router should we decide to switch her to an FTTP provision - I want to be sure that I have considered all possible options so I appreciate your feedback.

I had read that existing DECT handsets may work with a VOIP a capable DECT base station such as the Gigaset N300A or other equivalent, but what concerns me is that compatibility across vendors appears to be very much a mixed bag. I guess it might be worth a try. The existing DECT handsets are BT4500, originally chosen because of their large buttons and amplification feature. I think if I was going to get a VOIP capable base, then would seem sensible to also get the handsets that were designed to work with it. The base station on its own + BT4500 handsets might be worth a try and add base vendor handsets later if there is a problem, but that is a more expensive way to buy the VOIP capable kit .

Yealink comes up a lot, and I have also become aware of Gigaset as VOIP equipment brands. Yealink appear to have the edge in reviews and comments. The VOIP provider recommends either one of these brands so it is likely that I would choose one of these if I went down that route.

I is interesting to hear different views and sometimes it might e worth "biting the bullet" for peace of mind so I am still considering all options including a purchase of a Yealink or Gigaset complete kit with base station and matching handsets.

Edited by TruthDigital (Thu 11-Sep-25 19:51:36)

In reply to a post by burble:

Talktalk supplied us with a Grand stream ATA, plugged our old Panny Dect phone into it and it seemed to work fine. After porting to A&A tried to reconfigure the ATA, but no luck, it wouldn't respond to ***, not sure if TT have it locked down, or there's some other reason like being older Dect phone, so if your house phone can reconfigure the ATA be prepared to use that phone to reconfigure for your parents line.

Thank you for the heads up. Not sure what you mean by the "house phone can reconfigure the ATA", but doesn't it have a web portal that you connect to for configuration?

I don't have an ATA at my parents house yet, but our handsets and theirs are BT, just different models. I have BT8500, she has BT4500. If I purchased a Grandstream, I would set it up and test it here first, then once I set up their VOIP contract, I would just re-configure it for their VOIP account and VOIP//landline number.

I also had an idea to set up and RPi at their end so that I could remote in and diagnose/manage devices on their network. I would need a static IP for that but I heard that PlusNet are no longer providing those? If that's the case, its another slight complication as I would then have to change BB provider as well.

We have a dg4134 router with a BT8500 plugged into it with a voip from Andrews and a
Arnold. Runs exactly like our landline used too on PTSN, Infact my 89 years old mother doesnt notice the difference.

In reply to a post by iannewson:

We have a dg4134 router with a BT8500 plugged into it with a voip from Andrews and a
Arnold. Runs exactly like our landline used too on PTSN, Infact my 89 years old mother doesnt notice the difference.

Interesting device. Never heard of Technicolor routers before but the blurb says it is vendor agnostic. Since it has VDSL connectivity, it would probably work on the existing FTTC provision. Not sure what happens if/when we move her to fibre?

They used to be called Thompson.

Not sure, Ive only used it on FTTP as it was supplied by Giganet when I joined.

Have a Grandstream HT802 and a Gigaset GO-Box 100 to play with too but havent had the time to (

I'm posting this from memory.
For the Grand stream ata801(?) you need to connect phone then punch in ***20(?) this should give you the address so you can reconfigure the ATA, this doesn't work for me, but I'm using gswave on my mobile so not an issue for me and I've not investigated further.

Trying an old N300 from eBay may be worth a punt as test? I think I tried some BT handsets on mine once and they basically worked, but I can't recall 100%

I've had great success on eBay, with picking up a Gigaset N300AIP (the 'A' indicates the version with 3 answerphones) and a fairly random selection of compatible Gigaset DECT/IP phones (up to 6 phones). Connecting the N300 to an Ethernet port on my router or switch, to one or more chosen VoIP suppliers, gives a simple trouble-free service. No messing with the ISP's DV, or an ATA, or struggling with an old phone into a phone socket on a router. It's all cheap enough for experimenting and easily replaced if anything fails, which hasn't happened in 3 years.

Edited by cjn (Thu 11-Sep-25 22:53:31)

In reply to a post by iannewson:

They used to be called Thompson.

Not sure, Ive only used it on FTTP as it was supplied by Giganet when I joined.

Have a Grandstream HT802 and a Gigaset GO-Box 100 to play with too but havent had the time to (

Was just wondering ho it connects to the FTTP provision but I missed the red WAN port on the right hand side.

In reply to a post by cjn:

I've had great success on eBay, with picking up a Gigaset N300AIP (the 'A' indicates the version with 3 answerphones) and a fairly random selection of compatible Gigaset DECT/IP phones (up to 6 phones). Connecting the N300 to an Ethernet port on my router or switch, to one or more chosen VoIP suppliers, gives a simple trouble-free service. No messing with the ISP's DV, or an ATA, or struggling with an old phone into a phone socket on a router. It's all cheap enough for experimenting and easily replaced if anything fails, which hasn't happened in 3 years.

This does sound like an interesting idea and I see there are both used N300 and N510 units available, but not N300A's. One thought: the BT4500 has an answerphone built in which mum operates using the buttons on the base unit. I don't see any buttons or message display on the N300A and I can't expect mum to use the handset. She will just get confused with the menus. She doesn't use or have a laptop or computer. She does have an Alexa, but I don't know whether it can hook into a DECT or VOIP base? Its just one aspect that I need to consider carefully.

Having said that, a used N300 base on eBay is cheap enough to try an experiment with. Might even be able to use it here instead of the SPA112, so am considering it.

Edited by TruthDigital (Thu 11-Sep-25 23:06:34)

In reply to a post by TruthDigital:

I don't see any buttons or message display on the N300A and I can't expect mum to use the handset.

The answerphone aspect could be the decider. The N300A uses buttons on Gigaset handsets to access.

The BT handsets may work with an N300 but they'll only function as phones. The answerphone in the basetation won't be active any more in this configuration.

Revised advice - try an ATA with the existing DECT phones but if you have issues with echo think about leaving the ATA and answerphone in place but add an IP DECT basetation for the handsets.

Edited by ferretuk (Fri 12-Sep-25 09:08:07)

I think used N300A are still around if you search eBay long enough. I managed to get a second one to keep as a spare in case of failure. The N300A with Gigaset phones will cause a flashing red light on the phones' keypads to indicate a missed call and/or a voice message. Neither the N300 nor the N510 has an answering machine. The base unit has no need (or even the facility) to be directly accessible once set up and paired with each phone, as it can be fully configured via its web page. Allows 6 phones and 6 VoIP accounts.

The n300/n300a have an analogue port along with a rj45.

The n510 hasn't.

The n510 allows more parallel calls than the n300. Gigaset has rebranded the n300 to the Go box 100.

The analogue port on the N300 is only for connection to an existing fixed Line (landline). It doesn't allow connection of an analogue phone to the system. That would have to be achieved via a router with a suitable port, or some other device. Of limited future appeal.

In reply to a post by ferretuk:

In reply to a post by TruthDigital:

I don't see any buttons or message display on the N300A and I can't expect mum to use the handset.

The answerphone aspect could be the decider. The N300A uses buttons on Gigaset handsets to access.

The BT handsets may work with an N300 but they'll only function as phones. The answerphone in the basetation won't be active any more in this configuration.

Revised advice - try an ATA with the existing DECT phones but if you have issues with echo think about leaving the ATA and answerphone in place but add an IP DECT basetation for the handsets.

I think I came to the same conclusion this morning. The N300 can't connect an analog phone as per cjn's comment. The N300A apparently doesn't pass the necessary signals for the answerphone on the DECT phone to work. Neither the Gigaset nor the Yealink VOIP phones have answering machine control on the base station. On the other hand, the GrandStream ATA supposedly works fine with and existing DECT handset and answerphone. The Cisco equivalent ATA is far more expensive, so that leaves the GrandStream HT-802 looking like the likely candidate. I am not sure whether there is any mileage going for the HT-812 (with built in router) but looking at the spec sheet, the router functions look very basic anyway so I am leaning towards the HT-802 and sorting the router along with the BB provision. If we go fibre, then presumably the ISP will provide us with something. If we stay FTTC, then the existing one should be fine assuming I can set QoS for VOIP on it.

Edited by TruthDigital (Fri 12-Sep-25 13:17:20)

In reply to a post by cjn:

The analogue port on the N300 is only for connection to an existing fixed Line (landline). It doesn't allow connection of an analogue phone to the system. That would have to be achieved via a router with a suitable port, or some other device. Of limited future appeal.

Yeah bad wording on my part. meant rj11 to pstn line.

In reply to a post by Taras:

In reply to a post by cjn:

The analogue port on the N300 is only for connection to an existing fixed Line (landline). It doesn't allow connection of an analogue phone to the system. That would have to be achieved via a router with a suitable port, or some other device. Of limited future appeal.

Yeah bad wording on my part. meant rj11 to pstn line.

N.P. Understood what was meant. I think your last sentence does sum it up unfortunately. I might be able to use Gigaset or other DECT handsets with it, but without an answerphone so it doesn't really fill the requirement. Neither, it seems, does the N300A.

In case the N300A, plus Gigaset phones giving answer phone and missed call notification, is a possible answer, this looks like a good basis for experiment:

https://www.ebay.co.uk/itm/406215041718?_skw=n300a&i...

I'm wondering if your making it more complicated than it needs to be? If you have existing analogue phone that she is comfortable using, you just need the correct hardware to convert VoiP to analogue. A lot of the major ISP's routers have this. I've personally used a Fritz!Box 7530 AX and a Linksys PAP2T so far. They both weren't the easiest to setup with my A&A voip service but once I got some bugs figured out they work flawlessly.

The digital phones are nice but it's extra cost. It didn't make sense to me.

Edited by LeJimster (Mon 15-Sep-25 19:31:45)

In reply to a post by LeJimster:

and a Linksys PAP2T so far.

the pap2t and spa mentioned earlier are riddled with exploits. and i suspect most haven't been patched

In reply to a post by LeJimster:

They both weren't the easiest to setup with my A&A voip service but once I got some bugs figured out they work flawlessly.

voip providers don't always provide all the info. I had to play with a softphone to get it to work and then transfer the settings

I agree with LeJimster, I like to keep things simple. I'm with Zen and use their digital voice service. The Fritzbox they supply has a DECT base station built in but rather than pair all the phones to the Fritzbox I just plugged the existing base unit into the phone port on the router and it woks fine. A lot less hassle for me!

Edited by HughA (Tue 16-Sep-25 09:16:18)

In reply to a post by iannewson:

We have a dg4134 router with a BT8500 plugged into it with a voip from Andrews and a
Arnold. Runs exactly like our landline used too on PTSN, Infact my 89 years old mother doesnt notice the difference.

Does the BT8500's TrueCall screening function work ok as well?

In reply to a post by astanden:

Does the BT8500's TrueCall screening function work ok as well?

TrueCall functionality is contained within the BT8500 system. ie it requires no interaction with the line once the call is established over the network, so if you do have a problem, it won't be that.

Works just fine with me. Phone doesn't ring unless call is known or announced (my groundwire app will ring once before truecall jumps in). Answerphone works fine too.

In reply to a post by DFScale:

In reply to a post by astanden:

Does the BT8500's TrueCall screening function work ok as well?

TrueCall functionality is contained within the BT8500 system. ie it requires no interaction with the line once the call is established over the network, so if you do have a problem, it won't be that.

In reply to a post by cjn:

In case the N300A, plus Gigaset phones giving answer phone and missed call notification, is a possible answer, this looks like a good basis for experiment:

https://www.ebay.co.uk/itm/406215041718?_skw=n300a&i...

Thank you for the suggestion. I did agree and my apologies for going quiet for a while. I have been watching this item for the last week and although I had bid with a good margin, I managed to acquire it today for only a little more than the original bid price. For less than £40 it is certainly worth an experiment. I could have paid that for the N300A on its own so having the 4 handsets to go with it seems a good deal, even if not all of them work. Hopefully it should arrive in the next few days so we will see.

I did also pick up a Grandstream ATA quite cheaply so have both options to test. One of them will probably replace the SPA112. I have got the Grandstream mostly set up and working, but its behaving a bit oddly with the answering machine on the BT8500 giving me a series of beeps (similar to the engaged signal) for several seconds after the remote end has hung up. There is probably something in the configuration that needs to be tweaked. I thought the setup would be less complex than the SPA112, but it seems to be more so and the web GUI is rather slow, but it seems to work for most part.

Edited by TruthDigital (Thu 25-Sep-25 21:49:54)

I hope it all works well for you. In the event of any of the phones not working you can always pick up replacements on eBay. I have got a bit carried away by upgrading a couple of my basic C57XX phones with more modern examples (still on eBay). My latest SL750H was brand new and is lovely.

the SL750Hs are quite nice.

I have used a Cisco SPA112 to connect to Voipfone for the past 10 years. It has been fine.

In addition I have a Gigaset N300 Dect base station and several Gigaset phones. None of the equipment will work in a power cut so I would use my mobile phone. I might have to drive my car to find a mobile signal.

The N300 can also connect to A&A and Sipgate accounts.

Voipfone recently introduced an Android app so my mobile phone now also rings when there is an incoming call.

In reply to a post by cjn:

I hope it all works well for you.

So do I. Not had that much success with the Grandstream HT-802 so far. It kind of works sometimes with my A&A account, but sometimes shows the phone as off the hook and the handset then seems to think that the BT 8500 call blocker is in operation, so its a bit unreliable.

It doesn't work at all with the new A&A account and number I just got for my parent. Just says that the number was not recognized. Having said that I also tried a SIP client with that number and it wouldn't work either, which rules out the ATA as the cause. Will have to talk to A&A about that on Monday.

Edited by TruthDigital (Sat 27-Sep-25 22:51:56)

In reply to a post by TruthDigital:

Having said that I also tried a SIP client with that number and it wouldn't work either, which rules out the ATA as the cause.

What's your router? My parents have a HT802 connected by Ethernet to a Virgin Media Hub 3 and no issues with their A&A telephone account. I use my A&A account using Acrobits Softphone on my smartphone.

In reply to a post by jchamier:

In reply to a post by TruthDigital:

Having said that I also tried a SIP client with that number and it wouldn't work either, which rules out the ATA as the cause.

What's your router? My parents have a HT802 connected by Ethernet to a Virgin Media Hub 3 and no issues with their A&A telephone account. I use my A&A account using Acrobits Softphone on my smartphone.

Thanks. The router is a Vigor 2860ac and works without any problem with my own account when using the either the Cisco SPA112 or a SIP client on the PC. The SPA112 has been set up and in use for a number of months.

Its only when using the new account I purchased for my elderly parent that neither ATA nor SIP client work. The ATA or client registers but can't dial out. Trying to call the number results in a "number not recognized" recording. While testing the Grandstream HT-802 I disconnect the SPA112 from the network to avoid any routing confusion. The Grandstream is dog slow and it does take some time for the admin pages to load and also the line status to update on the Status page. Can't say that I am that impressed with it. However, because both the ATA and the SIP software client fail, I don't think that the ATA is the issue here. Since the router works fine with the other account, I don't think its the router either, but am open to suggestion.

BTW, the router is some years old but has been stable on our current FTTC connection. At some point in the not too distant future we will be upgrading to full fibre and I am aware that the Vigor will need to be replaced with something that can handle a much higher throughput. Was considering the OpenWRT Two which I hope will be available by then. WiFi is disabled and not handled by the Vigor but by separate devices which are capable of WiFi6 (not sure about 7).

Edited by TruthDigital (Sun 28-Sep-25 10:20:07)

I've not used draytek in years, but some routers have SIP "assistance" features which you will need to disable, but if it works with the elderly Cisco SPA112 then this is unusual.

AAISP's team may be able to help but in many cases you can only run one SIP service at a time through a single IP NAT router such as the Draytek; and if the Draytek itself has SIP voip functionality that would need to be disabled.

In reply to a post by TruthDigital:

Its only when using the new account I purchased for my elderly parent that neither ATA nor SIP client work. The ATA or client registers but can't dial out. Trying to call the number results in a "number not recognized" recording.

Got on to A&A this morning. They "made a change" at their end with the result that the account/number can now dial and receive calls using the SIP client. Hopefully it will now also work on the Grandstream, at least to the same somewhat unreliable degree that my existing account does.

Is there anywhere that I can find a setup guidance for the Grandstream with settings for the UK BT/OpenReach telephone network? I have found the odd post or two, but now concrete instruction. A&A have a screenshot but in conversations with the A&A tech, I was asked to change one of the settings, so the information may be out of date. Between that and the posts in question I have been able to piece together a config that kind-of works, but it would help if someone has a working config for a DECT phone with answerphone and BT call guardian.

In reply to a post by TruthDigital:

Between that and the posts in question I have been able to piece together a config that kind-of works, but it would help if someone has a working config for a DECT phone with answerphone and BT call guardian.

There are no specific requirements for a DECT phone, an answerphone or BT Call Guardian. They all work Plug and play on a standard PSTN line. So your struggle is to establish how to set up the ATA to provide a standard UK PSTN interface. I am reluctant to post a full config, partly because I would have to edit out sensitive information and be sure I had done it and partly because I was making best guesses, so my config is not necessarily right and may be full of rubbish. But if you want help on specific settings, I can tell you what worked for me.

My phones are BT8600 and they only worked after a fashion until I gave them fresh batteries.

I understand what you mean regarding sensitive information.

I have set SLIC to 'UK' and Caller ID Scheme to 'SIN 227 BT' which I found on another forum, but there are lots of other SIP settings besides the username/password, phone number and sip server. I have no idea whether any of them are correct or not. For example, for the URI scheme, the A&A sceenshot shows 'sip' but the default is 'sips'. Seems to work the same with either setting.

A&A's guide suggested setting Unregister on reboot to 'Yes'. I have options for 'All' or 'Instance'. The DTMF method settings are different to the SPA112 and the value (AVT) set on the SPA112 it not available on the Grandstream. Most everything apart from connection details and the SLIC and Called ID Scheme are set to defaults. I don't know what Vocoder or DTMF Method settings I am supposed to use?

If it does the basics, ie you can pick up, seize the line, dial out, hang up, get the phone to ring and answer, then effectively the SIP/VoIP side of things is sorted. Your remaining problem relates to how well the ATA emulates the interface at a BT Master Socket

If you can dial out, then DTMF is good enough. If you can hear a reasonable quality and similarly be heard, the the codecs [vocoders] are fine. I have a shed load available and have never had to fiddle with this. As for caller id, the range of choices is constrained enough that you can just try until you find one that works. This is purely local between the ATA and the phone, so if it works once, it should always work.

Like you, I am normally inclined to want to fix down every last setting. I would even want the ATA to have a simple menu where you just select the country and all the settings are done for you, But there are so many different standards - even within the UK - that I can see why ATA vendors don't do this. So I have accepted that I set what I know and I do the best I can with the rest. And that works for me.

It does work generally speaking. I can dial out and receive calls and the BT call guardian thing answers and asks my name, but weird things happen when the call is hung up with numerous beeps and sounds being heard for a few seconds after the caller has hung up, but before the line actually disconnects at the Grandstream/DECT phone end. This doesn't happen on the SPA112 which disconnects cleanly. I would like to be able to nail that down if possible. I am guessing that its related to signalling between the Grandstream and the BT 8500.

Like I said, change batteries on the BT8500, before trying to find a setting. It is probably cheaper than your time trying to find a fix. This cured my BT8600 of its random behaviour.

Try looking for "Loop Current Disconnect" in the Grandstream FXS Port page.

If disabled, enable, apply and update.

Changing this setting stopped the answerphone running for 30 secs or so after an incoming call is terminated using an HT801 V1 and BT Decor 2600 (corded handset with Trucall + answerphone).

I'd second this. All my original 6 Gigaset phones were used, from eBay. They all worked fine until 2 of them started being inconsistent. Batteries apparently fully charge OK, but we kept getting disconnections and a blank screen in the middle of a call. I replaced the 2 AAA batteries in each phone (highpowertech.com from China) with new Energizer rechargeables, and all is now fine.

In reply to a post by DFScale:

Like I said, change batteries on the BT8500, before trying to find a setting. It is probably cheaper than your time trying to find a fix. This cured my BT8600 of its random behaviour.

Noted. Will try that.

In reply to a post by cjn:

I'd second this. All my original 6 Gigaset phones were used, from eBay. They all worked fine until 2 of them started being inconsistent. Batteries apparently fully charge OK, but we kept getting disconnections and a blank screen in the middle of a call. I replaced the 2 AAA batteries in each phone (highpowertech.com from China) with new Energizer rechargeables, and all is now fine.

Thank you. I have also just received the N300A plus the Gigaset handsets today. Everything looks in a good clean condition. The handsets all powered up when dropped into their charger cradles which is a good start and are all charging as I type. I will hopefully get some time to set up the N300A tomorrow and we will see how it goes. This is worth knowing should any of the handsets play up.

In reply to a post by BarkingMad:

Try looking for "Loop Current Disconnect" in the Grandstream FXS Port page.

If disabled, enable, apply and update.

Changing this setting stopped the answerphone running for 30 secs or so after an incoming call is terminated using an HT801 V1 and BT Decor 2600 (corded handset with Trucall + answerphone).

Thank you. Due to the recent family emergency I haven't had much time to experiment for the last couple of days, but hopefully will be able to give this a try tomorrow.

Edited by TruthDigital (Wed 01-Oct-25 20:52:40)

I set up the N300A and C530 handsets yesterday and have to say it and they work very well. The batteries in the other two handsets either didn't hold power or just barely. I put two sets of fresh batteries into handsets 1 and 2, and the "good" sets into the other two. I ordered and have some more on the way to replace the latter. I have to say I am very pleased with it. Dialling out seems faster and the audio quality is very clear. I can also receive calls from both VOIP numbers assigned to my account.

In reply to a post by BarkingMad:

Try looking for "Loop Current Disconnect" in the Grandstream FXS Port page.

If disabled, enable, apply and update.

Changing this setting stopped the answerphone running for 30 secs or so after an incoming call is terminated using an HT801 V1 and BT Decor 2600 (corded handset with Trucall + answerphone).

This morning, I found and configured this setting on the Grandstream and it does indeed solve the problem. The BT Call Guardian and the answering machine now work without any unusual noises on hang-up and it disconnects cleanly and immediately. Thank you for that suggestion.

The existing batteries in the first two BT8500 handsets were fine - I had replaced them less than a year ago with a set of known branded ones so they ought to have been. The set in the third handset had not been replaced because it was still working "OK" at the time and I didn't have sufficient new ones. I had intended to buy some more and replace them, but over time had forgotten about them. The batteries in that one are no longer holding charge for any length of time so will be replaced once the new batteries arrive.

All in all, I think we have success and a solution for both households so I would like to thank everyone for their helpful and supporting comments.

Edited by TruthDigital (Fri 03-Oct-25 13:37:25)