FTTP and digital voice - how does bandwidth allocation work

Hoping an ISP or Openreach (OR) person can advise me on this.

Have Zen FTTP delivered over OR fibre (installed 2018) and upgraded to 300 Mbps down and 47 up in Feb on a retention deal.

Am using one of their Fritzbox 7530 routers and am preparing to ditch my landline and switch to digital voice (mobile reception is abysmal here).

Also had some issues with a phone system at work which made me think (Zen support have been great but can't find anything, I've collated log files and am waiting to hear back from colleagues who spend their day managing that particular system) however it got me thinking....


I'm currently weighing up whether to go with Zen for digital voice or Andrews and Arnold (ran a quick test with them back in 2020)

Now I'm assuming if you go with a single supplier they slightly raise the upstream and downstream on OR so that even if the connection is maxed out DV will still work and if I were to stick with Zen for the connection and go with A&A for their voice service this wouldn't happen or can I request a modification to accommodate this?

A&A would be cheaper on the basis that the phone isn't used all that much.

Hope this is clear and thanks for help in advance.

No CP, Zen or any other is able to raise the speeds to add a bit extra for VOIP, it can't be done that way. The correct way is to use QOS (Quality of Service) settings on the router to reserve a small amount of prioritised bandwidth for VOIP traffic, the speeds required for VOIP are quite low.

The question is do CP supplied routers support this and is something that will be set up by default? I don't know, my router is an enterprise grade device and various protocols can be configured with different priority levels and bandwidths if required.

You need to ask Zen how they give priority to VOIP traffic.

If it helps, I've been using A&A VOIP over my 80/20 FTTC connection without any issues or any QoS rules set, despite lots of other network activity.

On a 330/50 service you'll be just fine.

In reply to a post by techguy:

I'm assuming if you go with a single supplier they slightly raise the upstream and downstream on OR so that even if the connection is maxed out DV will still work

As the digital voice is not on its own Vlan it wouldn't help, if there was a way of adding another 128Kbps required for the digital voice that would still get saturated if you try to max out the broadband service.

In reply to a post by ferretuk:

If it helps, I've been using A&A VOIP over my 80/20 FTTC connection without any issues or any QoS rules set, despite lots of other network activity.

On a 330/50 service you'll be just fine.

That's reassuring to know, thanks.

techguy

You need to ask the ISP.

There are several ways to provide VOIP.

1. Over the top VOIP. Just VOIP in with everything else.
2. As above but with QOS enabled to prioritise the VOIP packets.
3. Set up on a separate VLAN (Takes approx. 128Kb from Up and Down capacity) BT's implementation is like this.

The ATA (CODEC) also make a difference as best quality voice is very small packets (10 -20ms packets) but small packets decrease the available Bandwidth as you do not fill the available frame and increase the router load. This should not be an issue with a reputable ISP router.

Look up G711 / G 729,/G723 etc.

Lower quality VOIP would use bigger packets
if using 2. you need to make sure the VOIP is the highest priority.

Unless you are really hammering your connection all three work just fine most of the time. I would expect any Router with a dedicated voice port to use 2 or 3. 3rd party VOIP often uses 1 but works just fine for most people with Speeds of over 10Mb upstream. Speeds under 10Mb upstream may occasionally struggle using 1...

The Fritz!Box has excellent QoS built-in, and defaults VoIP to the realtime class. I have mine configured with A&A and it works beautifully. It would work just as well with Zen’s voice service.

I added three Gigaset DECT phones and paired them directly to the Fritz!Box. I configured the Fritz!Box to sync my contacts from iCloud so the contacts on the phones match my iPhone / Mac.

In terms of mobile coverage, I always select a mobile service that supports wifi calling and text (Vodafone, BT Mobile, T-Mobile and many more). If the phone supports it, calls and texts run over wifi instead of the mobile data network. Dead handy in places with wifi but no mobile signal; like my recent holiday home in the Lake District. Could be useful if you have poor coverage at home.

In reply to a post by techguy:

In reply to a post by ferretuk:

If it helps, I've been using A&A VOIP over my 80/20 FTTC connection without any issues or any QoS rules set, despite lots of other network activity.

On a 330/50 service you'll be just fine.

That's reassuring to know, thanks.

I use a VoIP system and even on my 36ish Mb/s FTTC broadband, I don't have any problem and that is also when the TV is streaming 4K.

I use Sipgate as my provider and a very old Linksys PAP2, you would have to really bang your internet connection to make a difference to VoiP.

If you were in a corporate with dozens or hundreds of simultaneous voice channels then you would be best placed to have them on a a separate VLAN and running QoS on all your routers and switches.

However for a domestic or small/home office internet connection with one or perhaps a handful of simultaneous VoIP channels there really isn’t much wrong with running VoIP plainly over the top without any dedicated bandwidth reservation or QoS. It will be fine.

I’ve run VoIP over a variety of broadband connections and terrestrial connections were never a concern. 4G/5G connections are generally OK too, however they are far more liable to delay and jitter variability - which will impact call quality - however that’s not a concern for you.

I hate to chip in amongst such illustrious company but I'm sure I recall being told many years ago that the frequency response of a voice telephone line was (iirc) 400Hz to 4KHz. A decent hifi system will provide a frequency response around 20Hz to 20KHz so on a line that is running at Megabit speeds it's really not something that you're going to notice.