The Intercom can go through to the phone, but the phone can’t auto answer the call.
The Header in INVITE doesn’t contain with “intercom=true” or auto-answer information.
When receiving INVITE message with any of following Header, phone will answer the intercom automatically:
2/ Alert-Info: auto answer
3/ Alert-Info: info=alert-autoanswer
4/ Alert-Info: answer-after=0
First one is the default setting on the phone. Above 2 to 4, Configure the phone via auto provisioning to accept the Header that is supported by the server side, the configure feature please refer to below， after provisioning, the alert-info will be added to INVITE Header:
For example: account.X.alert_info = <sip: xxx@xxx >;info=alert-autoanswer;delay=0
Any further support, please feel free to contact firstname.lastname@example.org