2024-08-15

Cool feature on VoLTE

Our SIP2SIM SIMs run through ONSIM/Tango, and uses VoLTE normally. OK a lot of acronyms, I know.

The key point is we feed the call to the mobile network using SIP.

SIP allows the calling number to be set with a number (well, technically anything in the local part of the sip address) and a name.

Eg. I could have From: "Adrian" <sip:401@whatever>

On my SIP phone on my desk it shows both Adrian and 401, which is great. It has options to show one or the other or both.

I use this feature in our call routing, so, for example, if someone calls my 02000 number, I prefix the name part with a 2, and then the calling number. Similarly if someone calls my 0800 number I prefix it with 080. That way, even if all I can see is the name part, I get to see the calling number and a prefix indicating which of my numbers was originally called. In hindsight I may make the 0800 just have 8 as 080 then 0 looks even more confusing at first.

For example, this call:

As you see, the name part is 0800759...

What I have noticed is that the name part gets all the way to my mobile (iPhone).

I know this because of the missed call list.

Sadly when the call comes in, the main phone screen only shows the CLI, not the name part, which is a shame. Though on my Mac (which also shows the incoming call) it shows both.

It would be nice to have an option to show name, or both.

P.S. I cannot tinker with the actual CLI due to OFCOM rules - it has to be a plausible number. The fact the name gets through gives some hope of handling better local / internal CLI using Name field.

7 comments:

  1. Having the name come through is really nice. All we need now is for the world to move on from G.711 and start using wideband codecs.

    ReplyDelete
  2. Nice feature.

    Trying to replicate this myself using the Tag: field in clueless works for me to prefix the name shown on iPhone - however actual CLI (over ONSIM - desk phone is correct) is mangled and shows as +1 (1) (473)... for what should be +44 7473...

    ReplyDelete
  3. Your short CLI would not get through, which is why it is mangled. I believe we document it. Ofcom rules stopped us sending meaningful CLIs for internal calls, sadly.

    ReplyDelete
    Replies
    1. My 'short' CLI is only shortened for redacting it here. A bit clearer: CLI shows as +1 (1) (473)xxxxxx for what should be +44 7473xxxxxx. I was surprised that this wasn't passed through.

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    2. OK I am puzzled, we will normally only do the +1(1) thing for something that looks like an invalid CLI, can you email support with details of the call time and number so we can check the logic.

      Delete
    3. On further investigation I think this explains what's happening as I am calling myself to test this out:
      "Unfortunately it also seems that a CLI that matches the number we have assigned to the SIM always reports as Busy even when the handset is not busy, so this two [too?] gets replaced in the same way." https://www.aa.net.uk/voice-and-mobile/sip2sim/technical/

      Delete
    4. Typo fixed, I suspect that may be the case. Stupid, I know, and nothing we can do sadly.

      Delete

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