I post it in General as I'm trying it in different devices.

How should the SIP Server mark an incoming call as intercom? With some manufacturers it is done via SIP Headers (i.e. "Call-info: answer-after=0") but I know it's not an standard. I tried that way but couldn't get it to work.
I haven't found this info in any forum or doc

Thank you

Hi Sir,

"Call-info: answer-after=0" simply means that the incoming calls want to be picked up automatically, it is not standard; in Akuvox product, we implement "intercom = true" to mark the intercom calls. You could see from the attached picture:

Thank you, it works like a charm.