Is there a way to place a SIP trunk call without explicitly setting the caller ID (such as through the P-Asserted-Identity or From header), and instead let the SIP trunk provider automatically apply the default caller ID assigned to the trunk?

I couldn't find enough info in the docs to answer your question about letting the SIP trunk provider automatically apply the default caller ID if you don't set it explicitly (like in the P-Asserted-Identity or From header). This can depend a lot on the provider's behavior, and the documentation doesn't cover this specific scenario. I'm escalating this to a human expert so you can get a clear answer!

Simply configure your SIP trunk credential and associate your phone number without setting caller ID headers, when you place calls via the API, the SIP provider will automatically apply the default caller ID assigned to the trunk..

@Smith (hasbulla) Technically speaking - the trunk provider can do anything they want, as long as you are using BYO SIP. What you are describing sounds a bit like "CallerID Circulation" or otherwise known as "CallerID Spoofing" - where outbound dialing operators will circulate the outbound caller ID across thousands of "random" caller ID numbers - in order not to be picked up by the various SPAM detection tools.