Multiple VOIP Phones for House (not DECT)

So currently have a Grandstream HT812 connected, and working with AAISP with two incoming lines, which are connected to Siemens SL56 DECT handsets, of which we have 4 !

These are getting very old, and it's about time to retire them as batteries are getting difficult to replace.

So I would ideally like to get 4xVOIP handsets, I already have a working Yealink AX83H and it works with AAISP, the only issue is

there seems to be an issue or not supported that incoming calls only ring the last registered device.
(as stated on the AAISP configuration panel), although contradictory info is given in the support docs, that all devices are rang!


It really seems a step backard to connect a Fritz Box (DECT)/Siemens N300 IP/Yealink DECT base station and then connect handsets via DECT

Anyone doing anything similar with multiple VOIP Phones. (non DECT)

You could use the Fritzbox with wired (or wireless) VoIP phones as well if you don't want to use DECT phones.
or run Asterisk or FreePBX on a Raspberry Pi.

my issue is when using VOIP with AAISP, not all the phones ring at the same time.

because it only rings the last registered device, so even if I had 4 x VOIP phones registered, it would only ever ring the last registered VOIP phone.

Dial-out is fine, the issue is running around the house trying to answer the only phone ringing

I want a simple system, not hosting my own PBX, I could do that with Unifi or 3CX

Edited by einsteinagogo (Mon 04-May-26 22:15:02)

Can't AAISP advise how to fix this? AIUI it should be perfectly possible to set them to all ring.

In reply to a post by einsteinagogo:

my issue is when using VOIP with AAISP, not all the phones ring at the same time.

The default was the AAISP system called all logged in devices. You might want to check to see if one of your devices is doing something like anti-spam calls where it answers but keeps ringing locally.

In reply to a post by ChrisAO:

Can't AAISP advise how to fix this? AIUI it should be perfectly possible to set them to all ring.

I can confirm that all phones on our AAISP VoIP ring at the same time. We have an AAISP supplied Zyxel router with phone ports on the back. Plugged into that we have one old-style wired phone and a set of four BT cordless phones. Then we have two mobiles with Acrobits linked to the AAISP VoIP and all phones ring simultaneously.

Simple

Gigaset n530 (newest version) (which replaces the n510 and n300s)

up to 8 dect handsets - 8 sip providers - 8 simutanious calls

and ebay the grandstream and possibly the yealink.


By saying no to dect you have made things complicated in an uneeded way

having a voip dect base station makes more sense than "voip phone" if you want to go that way use a mobile with a sip clinet.

In reply to a post by GonePostal:

In reply to a post by ChrisAO:

Can't AAISP advise how to fix this? AIUI it should be perfectly possible to set them to all ring.

I can confirm that all phones on our AAISP VoIP ring at the same time. ....Then we have two mobiles with Acrobits linked to the AAISP VoIP and all phones ring simultaneously.

same here n510 and acrobits

Hi,

AAISP do ring all registered devices.

Can you confirm whether any of the devices are behind NAT? If they are then what configuration have you created such that AAISP can actually contact all VoIP devices rather than just the last one that created a mapping in your router?

In reply to a post by ChrisAO:

Can't AAISP advise how to fix this? AIUI it should be perfectly possible to set them to all ring.

This is the contradicition from AAISP

1. Only the lasr registered device will ring - observed.
2. Multiple registered devices ringing is not supported by may work.
3. Wiki - Multiple registered devices will ring.

Confirmed by other Techie Nerds on other forums - multiple registered devices do not work, only the last registered device rings.

thanks for reply.

nope, only calls the last registered device, if I power off and try all is well with all VOIP registered devices, even tried SoftPhone!

In reply to a post by Taras:

Simple

Gigaset n530 (newest version) (which replaces the n510 and n300s)

up to 8 dect handsets - 8 sip providers - 8 simutanious calls

and ebay the grandstream and possibly the yealink.


By saying no to dect you have made things complicated in an uneeded way

having a voip dect base station makes more sense than "voip phone" if you want to go that way use a mobile with a sip clinet.

this maybe the way forward, just didn't want to use DECT

In reply to a post by Dassa:

Hi,

AAISP do ring all registered devices.

Can you confirm whether any of the devices are behind NAT? If they are then what configuration have you created such that AAISP can actually contact all VoIP devices rather than just the last one that created a mapping in your router?

Yes all devices are behind NAT, no configuration has been performed.

Why does AAISP state only the last registered device will be ring ?

and this has been confirmed now by three other techies on another tech forum.

Do you have this working on your VOIP with AAISP ?

AAISP stated to me in the logs, all devices were tried, but the first registered device didn't answer, only the last as per AAISP configuration panel.

Is this a NAT issue ? I'd be interested what is required to fix this. But surprised if I'm missing info on AAISP to fix this NAT issue, because it will be so common place.

So 4 VOIP devices configured identically, plugged into the same LAN and powered up at the same time but only the last one powered up rings for incoming calls? do they all work for outgoing calls? does it work if you plug them in to different LANs (e.g. take one and plug it in to a friend or families LAN who doesn't have a VOIP services).

In reply to a post by PCJM40:

So 4 VOIP devices configured identically, plugged into the same LAN and powered up at the same time but only the last one powered up rings for incoming calls? do they all work for outgoing calls? does it work if you plug them in to different LANs (e.g. take one and plug it in to a friend or families LAN who doesn't have a VOIP services).

Correct, only the last registered device as per AAISP -- Control Panel states this.

All work for outgoing calls.

and it's the same again if I take them anywhere, any LAN, last registered device rings - as per AAISP control panel - which sort of negates the NAT configuration thing ?

Again these observations are confirmed by 3 other VOIP users with AAISP, they threw in the towel and went with a VOIP base station and DECT or their own PBX !

In reply to a post by einsteinagogo:

Correct, only the last registered device as per AAISP -- Control Panel states this.

All work for outgoing calls.

and it's the same again if I take them anywhere, any LAN, last registered device rings - as per AAISP control panel - which sort of negates the NAT configuration thing ?

Again these observations are confirmed by 3 other VOIP users with AAISP, they threw in the towel and went with a VOIP base station and DECT or their own PBX !

Would have been nice if AAISP had given you a definitive answer to this scenario as it must be either possible or not.

Hi,

Yes, I have had multiple VoIP devices registered with AAISP and they all ring when the number is called. They have all been on separate IP addresses though, some might have been through NAT but not more than one via the same NAT gateway.

I strongly suspect that this is a NAT issue.

When you look at the AAISP VoIP config pages, what are the ports / IP addresses listed for the registered devices?

Is there any way to show how your router is maintaining the mapping between the internal port / IP address and the external port / IP address for each of your VoIP devices? Does your router have a VoIP ALG, is it enabled and if so exactly what functions does it do?

NAT and VoIP generally do not play nicely together and I can see ways that multiple VoIP devices on your side could each overwrite the NAT mapping in your router leaving only the last registered device properly connected.

PS: I assume you have read https://support.aa.net.uk/VoIP_NAT - particularly the part about having separate port configurations on the multiple phone?

In reply to a post by PCJM40:

In reply to a post by einsteinagogo:

Correct, only the last registered device as per AAISP -- Control Panel states this.

All work for outgoing calls.

and it's the same again if I take them anywhere, any LAN, last registered device rings - as per AAISP control panel - which sort of negates the NAT configuration thing ?

Again these observations are confirmed by 3 other VOIP users with AAISP, they threw in the towel and went with a VOIP base station and DECT or their own PBX !

Would have been nice if AAISP had given you a definitive answer to this scenario as it must be either possible or not.

It is very contradictory as stated

1. Wiki states all devices will be rung
2. Control panel Only last device is rung
3. Works but not supported

4. Support suggests creating a new telephone number and use that as a ring other number.

So two phones would then ring, but this is technically using two numbers and a forward!

Again other's tested have said this does not work, I've been testing this on and off for 2 years!

In reply to a post by Dassa:

Hi,

Yes, I have had multiple VoIP devices registered with AAISP and they all ring when the number is called. They have all been on separate IP addresses though, some might have been through NAT but not more than one via the same NAT gateway.

I strongly suspect that this is a NAT issue.

When you look at the AAISP VoIP config pages, what are the ports / IP addresses listed for the registered devices?

Is there any way to show how your router is maintaining the mapping between the internal port / IP address and the external port / IP address for each of your VoIP devices? Does your router have a VoIP ALG, is it enabled and if so exactly what functions does it do?

NAT and VoIP generally do not play nicely together and I can see ways that multiple VoIP devices on your side could each overwrite the NAT mapping in your router leaving only the last registered device properly connected.

did you read the post, about four devices being used at different locations (IP). and only the lasty registered device rings.

"NAT and VoIP generally do not play nicely together and I can see ways that multiple VoIP devices on your side could each overwrite the NAT mapping in your router leaving only the last registered device properly connected."

does this not negate NAT, as four seperate IPs will all register as a single mapping in the router?

Hi,

In reply to a post by einsteinagogo:

In reply to a post by Dassa:

Hi,

Yes, I have had multiple VoIP devices registered with AAISP and they all ring when the number is called. They have all been on separate IP addresses though, some might have been through NAT but not more than one via the same NAT gateway.

I strongly suspect that this is a NAT issue.

When you look at the AAISP VoIP config pages, what are the ports / IP addresses listed for the registered devices?

Is there any way to show how your router is maintaining the mapping between the internal port / IP address and the external port / IP address for each of your VoIP devices? Does your router have a VoIP ALG, is it enabled and if so exactly what functions does it do?

NAT and VoIP generally do not play nicely together and I can see ways that multiple VoIP devices on your side could each overwrite the NAT mapping in your router leaving only the last registered device properly connected.

did you read the post, about four devices being used at different locations (IP). and only the lasty registered device rings.

"NAT and VoIP generally do not play nicely together and I can see ways that multiple VoIP devices on your side could each overwrite the NAT mapping in your router leaving only the last registered device properly connected."

does this not negate NAT, as four seperate IPs will all register as a single mapping in the router?

So, to be clear, you arranged things so that all four phones were connected via different NAT gateways, or did you simply move all four phones to a different NAT gateway? In the latter case you are not proving anything (other than perhaps the two NAT gateways exhibit similar behaviour).

NAT of SIP is complex, as explained by the AAISP page I posted a link to and whether it works depends, in detail, on what goes on in the router. Making the ports (and port ranges for calls) different across the phones might help if they are all to sit behind the same NAT gateway.

In reply to a post by Dassa:

Hi,

In reply to a post by einsteinagogo:

In reply to a post by Dassa:

Hi,

Yes, I have had multiple VoIP devices registered with AAISP and they all ring when the number is called. They have all been on separate IP addresses though, some might have been through NAT but not more than one via the same NAT gateway.

I strongly suspect that this is a NAT issue.

When you look at the AAISP VoIP config pages, what are the ports / IP addresses listed for the registered devices?

Is there any way to show how your router is maintaining the mapping between the internal port / IP address and the external port / IP address for each of your VoIP devices? Does your router have a VoIP ALG, is it enabled and if so exactly what functions does it do?

NAT and VoIP generally do not play nicely together and I can see ways that multiple VoIP devices on your side could each overwrite the NAT mapping in your router leaving only the last registered device properly connected.

did you read the post, about four devices being used at different locations (IP). and only the lasty registered device rings.

"NAT and VoIP generally do not play nicely together and I can see ways that multiple VoIP devices on your side could each overwrite the NAT mapping in your router leaving only the last registered device properly connected."

does this not negate NAT, as four seperate IPs will all register as a single mapping in the router?

So, to be clear, you arranged things so that all four phones were connected via different NAT gateways, or did you simply move all four phones to a different NAT gateway? In the latter case you are not proving anything (other than perhaps the two NAT gateways exhibit similar behaviour).

NAT of SIP is complex, as explained by the AAISP page I posted a link to and whether it works depends, in detail, on what goes on in the router. Making the ports (and port ranges for calls) different across the phones might help if they are all to sit behind the same NAT gateway.

all four phones were connected using different ISPs, in four different physical locations, and routers, andf configurations etc

only the last registered device ever rang!

All phones could be used for outgoing calls.

on the AAISP page is the Registered Devices, it's make and model and version and Internet Outbound IP address

there are no other ports, configurations of anything

if we experiment with rotation power off and on, we can get every device to ring, but not all at the same time consistent wuth Last Registered Device rings. (observed by 3 others!)

Hi,

I have done a quick check and certainly with two devices registered they both ring at the same time. It sounds like you have either found a bug in AAISP's VOIP servers, specific to you and your friends or there is a weird configuration issue somewhere.

Separately, I note that the control pages are misbehaving at the moment and taking ages to update the list of registered devices but that doesn't appear to affect functionality.

You might see it as being a step backwards but we use a Gigaset N300a Base Station and six Gigaset C575a Dect handsets.

We have two separate VOIP providers, (Sipgate Basic and Voipify), with two separate VOIP lines and we can set via the N300a how incoming and outgoing calls are made/received by which DECT phones. - (We kept to Gigaset because mixing and matching systems can be more difficult).

In our case: all six phones ring when there is an incoming call on either line and if one of the six phones is in use then the other five phones ring if an incoming call comes in on another line.

This was set up within the N300a menu.

We have never used the Grandstream 812 but maybe there is a similar menu choice within the Grandstream 812

I am not sure how your VOIP provider would have any say in which of your phones rings as I suspect that is handled by your internal phone systems and not by you VOIP Provider.

If it is a VOIP provider issue the take a look at Voipify and ask them if your present setup would be resticted by them in some way.

https://www.voipify.net/?mtm_cid=235201820&mtm_kwd=&...

In reply to a post by Dassa:

Hi,

I have done a quick check and certainly with two devices registered they both ring at the same time. It sounds like you have either found a bug in AAISP's VOIP servers, specific to you and your friends or there is a weird configuration issue somewhere.

Separately, I note that the control pages are misbehaving at the moment and taking ages to update the list of registered devices but that doesn't appear to affect functionality.

it's never worked for me in two years, just revisting as more and more VOIP people leave landlines, I thought it might be me.

We also have more than one line, and it does not work on both.

and this has been observed by at least four people including me. (and AAISP support didn't really no why, other than suggest ring the other number)

Thanks for your help, may its time for a VOIP Dect Base

In reply to a post by Fido:

You might see it as being a step backwards but we use a Gigaset N300a Base Station and six Gigaset C575a Dect handsets.

We have two separate VOIP providers, (Sipgate Basic and Voipify), with two separate VOIP lines and we can set via the N300a how incoming and outgoing calls are made/received by which DECT phones. - (We kept to Gigaset because mixing and matching systems can be more difficult).

In our case: all six phones ring when there is an incoming call on either line and if one of the six phones is in use then the other five phones ring if an incoming call comes in on another line.

This was set up within the N300a menu.

We have never used the Grandstream 812 but maybe there is a similar menu choice within the Grandstream 812

I am not sure how your VOIP provider would have any say in which of your phones rings as I suspect that is handled by your internal phone systems and not by you VOIP Provider.

If it is a VOIP provider issue the take a look at Voipify and ask them if your present setup would be resticted by them in some way.

https://www.voipify.net/?mtm_cid=235201820&mtm_kwd=&...

Thanks we do have a N300A !

Maybe it's just time to ditch the Grandstream, (it crahes anyway!) and dedicated VOIP phone, that could be used just on the other line....

and we carry on using our DECT units, need to find batteries or purchase new DECT phones.

have you tried setting a delay here

When calls arrive for 0x they can try connecting to multiple possible targets, all at once, with optional delays:

In reply to a post by Taras:

have you tried setting a delay here

When calls arrive for 0x they can try connecting to multiple possible targets, all at once, with optional delays:

optional delays are not possible from the AAISP configuration, optional delays are only possible specifing different numbers, there is a Delay feature which I assume is the delay between each target but this does not work

they are all supposed to ring at the same time (it does not work)

Edited by einsteinagogo (Tue 05-May-26 17:12:27)

just to confirm we are talking about voip from aa.net.uk

We don't use AA as an ISP.

VOIP only, and don't use their router as well, maybe the issue

So it's like comapring apples and pears

only use their VOIP not ISP

In reply to a post by Taras:

just to confirm we are talking about voip from aa.net.uk

yes them but only VOIPP service no broadband

Only asked as my brain just refers to them as AA and i get confused when i see AAisp .......

then what i wrote about in the control panel about the delay stands. I found it there when i checked my account.

yes, there are two places, neither work for me or others!

Just upgraded firmware on all VOIP devices and set a delay of 30 seconds, and we will see if anything different happens

the interesting thing or statement in control panel reads

When calls arrive for 01xxx xxxxxx they can try connecting to multiple possible targets, all at once, with optional delays:

Now is a Target referring to a SIP phone underneath or Targets which is also underrneath, because support were suggesting they are different

Edited by einsteinagogo (Tue 05-May-26 22:15:53)

all you can do is try it ........

theres only 3 outcomes

it doesn't work
it helps
it breaks things

all are recoverable.

IP Lock is turned off I take it?

I have 4 devices logged in to my AAISP voip account which all ring ( although 3 are under one IP address and 1 is via an app on my phone)

In reply to a post by iannewson:

IP Lock is turned off I take it?

I have 4 devices logged in to my AAISP voip account which all ring ( although 3 are under one IP address and 1 is via an app on my phone)

tried on and off

what router are you using

In reply to a post by Taras:

what router are you using

Route at this test site is a Ubiquiti UniFi USG-XG-8

In reply to a post by einsteinagogo:

Route at this test site is a Ubiquiti UniFi USG-XG-8

I don't know Ubiquiti kit, but if it has a SIP ALG or any SIP support, disable it.

In reply to a post by jchamier:

In reply to a post by einsteinagogo:

Route at this test site is a Ubiquiti UniFi USG-XG-8

I don't know Ubiquiti kit, but if it has a SIP ALG or any SIP support, disable it.

No issues with outbound, or inbound on either device if it registers last.

Other has said SIP ALG is not rwssponsible for this issue, and it's only Yealink VOIP phones which do not ring, and that's when behind other types of router.

and the changes made yesterday to Yealink phone, stopped working so it was random.

Not fixed.

In reply to a post by einsteinagogo:

No issues with outbound, or inbound on either device if it registers last.

So last register working... does to me sounds like a NAT issue or a ALG (Application Layer Gateway) interfering with the SIP INVITE packets being sent to your devices from the voiceless gateway server. Debugging this sort of thing through NAT is hard, which is why AA talk about using them as an ISP and using IPv6 as that ensures each device has a public IP and NAT clever tricks are not needed.

I use my VoIP mostly on my phone with Acrobits, and there is no way you can control what the mobile networks or third party WiFi networks do.

Do your devices support STUN ? (Simple Transfer of UDP through NAT); AA support this, and you'll see the same comment about SIP ALG on the support page:
https://support.aa.net.uk/VoIP_NAT

I have an old Cisco ATA which I no longer use, and my smartphone app. My parents have a Grandstream ATA and a DECT base station plugged in, and they have the same app on two different phones, and all ring at same time. My parents use Virgin Media's basic router/hub they provide, and I have an ASUS router with RMerlin firmware and any SIP turned off.

No knowledge of Ubiquiti kit.

In reply to a post by jchamier:

In reply to a post by einsteinagogo:

No issues with outbound, or inbound on either device if it registers last.

So last register working... does to me sounds like a NAT issue or a ALG (Application Layer Gateway) interfering with the SIP INVITE packets being sent to your devices from the voiceless gateway server. Debugging this sort of thing through NAT is hard, which is why AA talk about using them as an ISP and using IPv6 as that ensures each device has a public IP and NAT clever tricks are not needed.

I use my VoIP mostly on my phone with Acrobits, and there is no way you can control what the mobile networks or third party WiFi networks do.

Do your devices support STUN ? (Simple Transfer of UDP through NAT); AA support this, and you'll see the same comment about SIP ALG on the support page:
https://support.aa.net.uk/VoIP_NAT

I have an old Cisco ATA which I no longer use, and my smartphone app. My parents have a Grandstream ATA and a DECT base station plugged in, and they have the same app on two different phones, and all ring at same time. My parents use Virgin Media's basic router/hub they provide, and I have an ASUS router with RMerlin firmware and any SIP turned off.

No knowledge of Ubiquiti kit.

Again only happens on the Yealink units.

and used all 4 Yealinks unit, logged into AAISP, from four different seperate public IP addresses, different router equipment, and only the last device registered - WORKED.

I think I'm just going to reuse the N300 and register DECT handsets, (as other's on other Forums have also found)

https://support.yealink.com/document-detail/31e6527a...

thats the config page in the manual ....... nothing shown under advanced - i suspect stun is in there in advanced

Ok, if you use a Fritzbox then the FB registers with AAISP. When a call comes in, all VoIP phones behind the FB will ring (if configured accordingly). I am with AAISP and use a FB7590, have my smartphone registered and two DECT phones, but you could also register wired SIP phones. You can then set up so that all phones ring on incoming calls.