t46g: intercom over speaker rather than headset?

[cm21]

I am setting up T48G's and am running into the same issue. I would strongly encourage an option or SIP header parameter, etc, that would ensure speaker mode for an intercom call. Please advise if there are any solutions.

Related to this, I'm unclear exactly what the T48G is looking for to tell it that an incoming call is "intercom". So far, the only thing that makes it auto-answer is setting the "Answer-After" header. However, at least with that method, the intercom settings "Accept Intercom" and "Warning Tone" seem to be ignored. It auto-answers the intercom call even if Accept Intercom is disabled.

I see through packet captures that for an outgoing call made from an "Intercom" DSS button, that the phone sets the URI parameter intercom=true. However, when that parameter is received on an incoming call it's not appearing to have any effect.

Can you clarify exactly which SIP options/parameters the phone uses for handling an intercom call?