I have an 8841 Multiplatform connected to a Grandstream IP-PBX and I want to enable the auto-answer feature for intercom calls only. Is there a way to configure the 8841 to only auto-answer calls with the alert-type "Intercom". I have several phones from different vendors that are able to answer intercom calls this way, but I am unsure of how to configure the 8841 to answer calls this way as it only gives me the option to auto-answer every call.