Moving to Fibre - SIP/VOIP app for mobile phone

I now have Fibre available but not yet taken up and while I am looking at keeping the landline, I am not that chuffed with Digital Voice, which seems only to be available with BT Broadband and their router, or with a lot of messing around with an Analog Telephone Adapter [ATA] and apparently no legitimate full VOIP solution for residential customers. Overall, I think with the radical change in technology, it is time to go for a full SIP/VOIP solution and eliminate ATAs, ie bite the bullet and avoid hybrid technology.

A further reason to go fully digital with the landline is that I intend to use the runs for the extensive PSTN to put in ethernet. So what I am planning is a small PBX, eg on a Raspberry Pi. I already have a SIP/VOIP phone working and I have a couple of 4 year old Android phones [Android 10].

So does anyone have any recommendations for
[1] SIP/VOIP apps which I can use to play around with this? Note that I need an app which is not hard programmed to any VOIP provider.?
[2] Any SIP/VOIP PBX software for Raspberry Pi?

[3] And can anyone tell me if I am wrong about it not being possible to have Digital Voice fully digital in the house?

Any and all help appreciated

Edited by DFScale (Sat 16-Dec-23 09:05:57)

1 - I use Acrobits Softphone ... it just works. Others may have the enhanced features of Groundwire. iPhone or Android. https://acrobits.net/sip-client-ios-android/
2 - Not my area, but I see others talking about 3CX, or for those very technical Asterix (https://www.asterisk.org/)

3 - "Digital Voice" is a name used by BT / EE broadband providers for the telephone service that their router ("hub") provides. Other companies use different names. Virgin Media for example just call it "Virgin Phone" but you connect to the router ("hub"), not the old wall socket. Even though they have nothing to do with Openreach's network. Sky I think call everything voice "Sky Talk" however its delivered.

The only advantage of using an ISP provided voice service is that they look after any concerns of QoS and you have one place to yell at when (if?) it stops working. Sometimes you pay more for this.

Edited by jchamier (Sat 16-Dec-23 09:42:33)

Seconded for Acrobits Softphone: it's a one-time payment - no recurring charges - and can be shared between your household if you have a family account with Google Play and presumably Apple too.

There are free options like Zoiper but they drain the battery on your phone much faster. Acrobits Softphone or Groundwire use native push notifications.