Propagation of CID in calls forwarded to PSTN

FreePBX 16.0.26
I have configured an extension, an inbound route, an outbound route and a trunk in order to forward to a PSTN number the incoming calls to a DID number.

In the extension I have set the PSTN number to which calls are forwarded in the follow-me list.

In the outbound trunk I have written the SIP credentials of the VOIP provider that gives me access to the PSTN. I have used a Dellmont provider.

This works; however the problem is that the Dellmont provider allows forwarding the caller id only if it is one of the CID’s that are registered in the Dellmont account. If the caller id is not in the authorized list, the call is received as anonymous by the PSTN phone.

This is line of principle is normal, because the Dellmont providers wants to avoid spoofing the caller id. But thus it is not possible to forward the CID in the forwarded calls, when using such providers in the outbound trunks.

Which VOIP providers exist, which can be used to forward any caller id in the PSTN forwarding in the outbound trunks of freepbx?

There are lots of choices. Almost all ‘wholesale’ providers allow arbitrary CLI. Some that don’t require a large commitment include Voxbeam, AnveoDirect, Thinq. Also many of the ‘app oriented’ providers such as Twilio, Plivo, Signalwire.

However, based on your previous posts I’m guessing that you are calling Switzerland mobile, and many of these providers have obscenely high rates to there.

I recommend that you try AnveoDirect. Rate via Bandwidth is USD ~0.08 to most CH mobiles. They give you a very small credit at signup (only enough for about 5 minutes), but you can still test quite a bit without making a payment, using calls that last only a few seconds or are unanswered.