Some general VoIP/SIP/DV questions for End of Landine talk

Hi. I'm a member of a local U3A Science and Engineering group and I'm giving a talk on the history of telephony and the end of the landline.

I've 99% completed the talk but have still some questions that so far the answers have eluded me. Perhaps you can help please. I've buddled them in 1 posting as I don't want to appear to be spamming with multiple posts. Please feel free to just answer 1 question.

Q1. Power to BT's Cabinets
When there is a local power failure, do the cabinets have UPS or perhaps even power from the exchange? (I suspect the answer is No!)

PS I'm aware that FTTP OTN is dependent on power but UPS can mitigate that for a while - I have 3 UPS and can keep IT equipment going for 1 to 2 hours and if I get battery storage then much longer. Mobile tethering is slow on my phone.


Q2. FTTP Firewall
I've seen in videos various BT FTTP home installations. In some, BT provide a router and then the user plugs that into their existing modem/router but this time into one of the ethernet ports. Wont this bypass the user's firewall?

I would imagine that some people would want to, for example, configure their router to block Digital Voice/SIP calls to premium numbers besides all the "normal" (read paranoid!) settings. I regularly get sniffing attempts.


Q4. Cross domain SIP calls
I've seen SIP providers offer free calls between their users (e.g. sipgate to sipgate) but surely calls to users with other SIP providers should be free as well as there is no real cost? (aren't SIP calls peer to peer once set up?)

I wonder if BT will be accepting inbound sip calls, e.g. to [email protected] where the no. is the user's landline number?

It's seems like the days of Compuserve before they built an internet email gateway. And even like the 1800s when the wired telephone systems were independent of each other.


Q5. VoIP Spam
With near zero cost what's to stop a deluge of SIP spam calls? Unlike emails, there is no content for the SIP provider to analyse.


PS U3A (University of the 3rd Age) is about learning new things in retirement and sharing with others.

Thanks for reading,
Alan

you may find this site interesting https://www.britishtelephones.com/homepage.htm

POTS lines are powered from the exchange, FTTC are powered locally, i guess there is some battery backup inplace.

Cross domain SIP calls - this is possible, but most systems will block this for security

did't read it but.....
https://www.thinkbroadband.com/guides/fibre-fttc-ftt...

Many thanks @copex

As it happens I did stumble across https://www.britishtelephones.com last night. It was very helpful with regard to Digital Voice. I wrote to the author to thank him and asked for some clarification and got a helpful reply this morning. The site also hosts a guide (from another user) on configuring Asterisk with Digital Voice that will be very useful when I eventually switch across.

I will look at the https://www.thinkbroadband.com/guides/fibre-fttc-ftt... page. A quick glance shows some technical info further down the page,

re power. britishtelephones site says ONT's have 4 AA rechargeable batteries in them but didn't say what for. Maybe to act as a power filter.

In reply to a post by Alan_Wilts:

re power. britishtelephones site says ONT's have 4 AA rechargeable batteries in them but didn't say what for. Maybe to act as a power filter.

That is now out of date, the ONT use to come with battery backup for the voice service that use to be presented on the ONT but both have been dropped some time ago.

Edit: added clarity

Edited by deleted (Wed 31-Aug-22 11:02:41)

The trouble with getting information from websites is that they are very often out of date or incorrect.

Openreach ONTs have never had rechargeable batteries inside them but in an external BBU (Battery backup unit). This was to provide power to the ONT to support Openreach FVA (Fibre Voice Access) if mains power was lost so phone calls could still be made for a short time.

Openreach have discontinued FVA (Stopped sale to new customers in March 2020) So ONTs no longer have any battery backup facility

It is now up to the CPs (Communication Providers) to provide digital voice with their Broadband services and they will decide if any battery backup is offered.

Hi Alan,

Please see my answers to your questions below and I hope they help you.

Q1
FTTC Cabinets usually have a UPS backup but they don't las long.
In longer power outages Openreach my send engineers to replace the batteries with fully charged ones when they run out.
For the ONT they used to come with a battery back-up but they don't anymore.

Q2
While you are correct the ONT plugs into an ethernet port, it does not bypass the firewall.
The routers provided for FTTP have a WAN port and all traffic will pas through the routers firewall unless it is changed in the configuration.
Even if the router has the ATA built in they have such stripped down functionality for basic users it is unlikely you will be able to do call blocking on them and will need to be done on the SIP server.

Q4
It is because when you dial a number that is with your provider it will see if it is in its database and route it across their network giving you a free call.
To get this functionality to work between providers you need need to dial [email protected] not xxxxxxxxxxx unless there can be a way for each provider to know who the provider is pf the other number and not send the call into the normal telephone network.

Q5
The only things you can do really are make sure your settings are secure to stop ghost calls and maybe have a block list to block spam callers

Thanks
Dan

Hi Dan.

Many thanks indeed for replying to all of my questions in a most helpful way.

re Q2 you say "The routers provided for FTTP have a WAN port and all traffic will pas through the routers firewall ..."

I was thinking where a user wants to use their own router. Having 2 routers wastes power and may complicate things. But I guess most normal users are happy to take what they are given, plug it in and if it works then fine. I'm with Zen and use my own router which is customised to my needs.

re Q5 SIP spam and stopping ghost calls and maybe have a block list to block spam.

I do with my POTS / Asterisk system with a 550 line script but it's pain to keep tweeking it. We can have no spam calls for a month then they come every hour or so for a few days. At least we sleep at night as all unknown callers at night get rejected and in the day I can push to VM.

best wishes,
Alan

Many thanks for responding and your post had useful info on how BT's provision has changed.

Agree, websites can have OOD info,

re Openreach ONTs have never had rechargeable batteries inside them

See https://www.britishtelephones.com/btdigitalvoice.htm... and page down a bit for a photo.


I've jet to go FTTP but I will contact my ISP to see how they provision the service.

Alan

Many thanks @dect for bring me up-to-date with the current situation.

Alan

re Q5. OFCOM have some plans to reduce SPAM calls with the move to VOIP. This will be to do with a database of owned numbers so that portability also works better but the originating number is validated with a specific operator so if being spoofed on a different network will be easily identifiable and therefore blockable by the VOIP operator.

They appear to want to police this with fines for VOIP operators hosting Spam callers ( or acting as pass through from abroad for UK spoofed numbers)

re Openreach ONTs have never had rechargeable batteries inside them

See https://www.britishtelephones.com/btdigitalvoice.htm... and page down a bit for a photo.

Hi Alan - yes that photo is of a Huawei 1+1 ONT and BBU fitted within a larger enclosure (I have one), and as noted hasn’t been fitted by Openreach for coming up to 3 years now. They had a voice port (hence the +1 designation) directly on the ONT (rather than an FXS voice port on the ISP supplied router) to access the now defunct Openreach Fibre Voice Access (FVA) product.

If you’re educating users that are yet to have (Openreach based) FTTP fitted then it less likely they will receive a Huawei ONT now (even a smaller 1+0 unit) as they are verboten, due to the UK government insisting on a phaseout of Huawei kit in our telecoms infrastructure.

Instead they will either get a Nokia or latterly Adtran ONT neither of which sport voice ports (they are 1+0 designated). There is a replacement Openreach 4 port Nokia in the works, but as yet has not been formally released.

You may want to also cover AltNets in your report. There are some 100 odd independent FTTP network builders active now in the UK. There’s a very good chance folks will be served by them with or without Openreach passing by.

Some ISPs will support users with setting up their own routers. Most ISPs can be used with your own router. A small number may choose not to provide the login information to allow you to use your own router. If your ISP will provide the login details then you can just replace their router with your own. The router used would be one that uses a WAN ethernet port rather than a DSL port - there are many routers on the market that support a WAN ethernet port so there is plenty of choice.

EDIT: One thing to bear in mind if using your own router on FTTP is if you are using the ISPs own VoIP service. Some of the ISPs, such as BT, provide the voice service via a phone port on their supplied router - if you ditch their router their own digital voice service won't work and you would have to provide your own (probably VoIP) service.

Edited by ian72 (Wed 31-Aug-22 16:52:22)

Q4. Cross domain SIP calls
I've seen SIP providers offer free calls between their users (e.g. sipgate to sipgate) but surely calls to users with other SIP providers should be free as well as there is no real cost? (aren't SIP calls peer to peer once set up?)

I wonder if BT will be accepting inbound sip calls, e.g. to [email protected] where the no. is the user's landline number?

It's seems like the days of Compuserve before they built an internet email gateway. And even like the 1800s when the wired telephone systems were independent of each other.

If you're a traditional incumbent telco like BT, there's probably little incentive (right now) to go down this road as it would completeley erode what little remaining revenue there is from landline calling.

Once PSTN is fully retired, in this country and also around the world, will legacy telco have any legitimacy in charging for calls? Probably not.

Brave new world. At least for us of a certain generation/age. My kids just message each other and hardly use their devices to talk - even when they're sat in the same room!!

Edited by Pheasant (Wed 31-Aug-22 19:36:27)

I have a 1+1 ONT , the Battery pack contains the batteries, not the ONT unit itself so my original statement, in my opinion is correct.

In reply to a post by danielhyde:

Q4
It is because when you dial a number that is with your provider it will see if it is in its database and route it across their network giving you a free call.
To get this functionality to work between providers you need need to dial [email protected] not xxxxxxxxxxx unless there can be a way for each provider to know who the provider is pf the other number and not send the call into the normal telephone network.

There is no @ key on my Gigaset phones.

Hi Michael - typically need to use a soft-phone for SIP URI calling as described by Dan.

Here's a quick briefing by A&A about it....

https://support.aa.net.uk/VoIP_-_Calling_With_a_SIP_URI

Not all providers (or devices) support SIP URI calling.

There is still infrastructure to pay for. Either via a subscription model, call charging or a combination of the two. Something has to pay for the equipment that is making it possible to do VoIP calls.

There is a cost of course but it is very, very minimal compared to traditional PSTN.

The actual “infrastructure” required for SIP is a tiny, tiny fraction of what’s required for ordinary PSTN infrastructure; there is some modest central server/computing infrastructure and software for the signalling and call setup. There is no heavy media processing or transcoding etc. Call media traffic generally passes directly from peer to peer so they don’t even need huge pipes centrally. The centralised SIP server(s) simply set up (and tear down) the sessions between endpoints.

Sipgate - which is extremely popular on this forum (and in general), have absolutely no infrastructure in the UK yet have thousands of customers. In the TDM world of PSTN there would need to be physical lines, exchanges, switches, interconnects, gateways. In the VoIP world you have SIP (amongst other some other VoIP standards) which is just another internet protocol running over the top of an IP connection.

You don’t actually need *any* infrastructure for direct SIP to SIP calls it is entirely possible to have direct peer calls (although usually a sign of spam calling).

If I look at what I have been paying the last 10 years or more, there is no ongoing subscription cost, the calls costs are only where calls break out into the PSTN and there are interconnect or landing charges levied by the telcos for entering or egressing their network gateways. If you call another number within Sipgate then calls remains free. As is for many other VoIP providers for their on-net calls.

Despite the capacity for call charges to massively reduce as PSTN is retired around the world, I expect that the current charging model for most providers won’t really change all that much.

I agree it is cheaper but they still need enough to pay staff, maintain and develop software, etc. There needs to be a cost somewhere and how they do that cost model is key to their survival as a business.

Pheasant - Thank you for the link. As I happen to have an A&A account I managed to make a SIP call to it using Linphone on an Android mobile. Quite interesting.

In reply to a post by ian72:

I agree it is cheaper but they still need enough to pay staff, maintain and develop software, etc. There needs to be a cost somewhere and how they do that cost model is key to their survival as a business.

Of course. That’s undeniable, but the cost base is of course spread much farther and there is not the huge level of upfront and ongoing maintenance cost as we have gotten used to with the PSTN.

Currently all pricing at least in the UK is highly regulated by Ofcom for call termination charges etc. it is very much a legacy charging and regulatory paradigm. Under the current rules nothing much will change until March 2026 when the current price caps expire.

There is every capability right now to enable virtual peer to peer VoIP call routing without having to resort to complex (and highly revenue generating) edifices like BT IP Exchange. But you can’t make a leopard change it’s spots. Incumbent telcos have been used to extracting revenue from voice for well over a century

In reply to a post by Michael_Chare:

Pheasant - Thank you for the link. As I happen to have an A&A account I managed to make a SIP call to it using Linphone on an Android mobile. Quite interesting.

Yes the Linphone client allows me to reach A&A Sales using the SIP URI (sip:[email protected]) without having any SIP accounts configured. So effectively a free call.

Edit: sip:[email protected] also works fine too, as would their other numbers for support etc.

Edited by Pheasant (Thu 01-Sep-22 19:20:31)

In reply to a post by Pheasant:

You may want to also cover AltNets in your report. There are some 100 odd independent FTTP network builders active now in the UK. There’s a very good chance folks will be served by them with or without Openreach passing by.

Hi. @Pheasant. Thanks for further info. Virgin Media have been busy in my street laying their cables in BT ducts I believe. I got a call from the salesman but declined. I'm not into media streaming etc. They have a far bit of the town covered already.

I've noted in the papers etc how many of these AltNets are rolling out across the country. Obviously trying to get there first. Some/many are offering GB speeds but I suspect they are aiming at businesses mostly or more "posh areas".