We are running with an up to date PBXact and a UK SIP Trunk from main UK Wholesale Provider.
The UK wholesale trunk has CLI flexibility turned on so we should be able to present any Caller ID number as the number we are dialing from.
If we call numbers within the UK all works perfectly. Whatever we put in the Extensions Outbound CID gets displayed correctly for the person we are calling.
Recently one of our clients has started calling someone in the USA who isn’t getting their correct Extension Outbound CLI number.
We have had limited success with a ChanSIP trunk to the provider, where 2 test numbers have been presented ok but other similar numbers were either presented as Unknown or as the main Network CLI.
Our trunk provider says our SIP headers are correctly formatted with the From and PAI information, however they can’t guarantee what international providers display at their end.
I understand they have no control of what is displayed at the other end, but as some numbers are being presented ok, is this something we can realistically fix?
The person we are test calling has an ATandT mobile in the USA.
I am currently thinking about getting a USA trunk just for testing to see how our numbers are displaying in the USA, but much harder trying to see how our numbers are showing on USA mobile phones.
I suppose initially I’m asking has anyone else ever experienced this sort of issue?
Am I wasting my time trying to fix it in my own dialplan code/Wireshark tests?
Do other MSPs use different SIP providers for international calls?
We have many clients running through these trunks and I would hate to have to turn round to them and tell them if they call anyone outside the UK their number may not be displayed correctly.
I shall supply Wireshark recordings shortly.
Any advice is welcome
PS – I have also tried PJSIP trunks to the provider but as we had limited success with one of our ChanSIP trunks we thought we would try to fix it on that first and then work our way onto the PJSIP trunk config next.