I've seen it mentioned a couple of times in this thread that these phones don't support intercom, but I've got several of them and intercom works great. Dialing the feature code for intercom that's set in FreePBX (*80) followed by the extension works fine for me (you just can't dial # at the end or it won't work). I also have them working with Paging. The only thing they don't seem to do is play the "beep" when the intercom / paging connects, like my Aastra phones do. Are others not able to get this to work?
Read my post above, I just tried before reading your post and found to my surprise that it works. That's skepticism for you
Also the 'beep' is there when intercom call comes in, maybe increase the sound level by pressing 'up' on the four way toggle while you are on intercom call (on the receiving end where beep should be heard). For some phones sound level is being adjusted only for the function of the phone you are just using, like Aastras that you say you have are like that.
As for the # sending the intercom call along which doesn't work - I found its best to get into the habit of pressing the green button to dial, even if you are off hook when dialing, it works to send the call - intercom or normal along.
For making on hook call, its not necessary to first press the green button, just dial your number and press it when done. I like that because I always felt telling your family members to press the # if they don't want to wait four seconds was kinda geeky for them, this is much better. Maybe it works the same way on Aastra phones too (using the hands -free button to send dialed number along).
The phone seems to be set to cut the sound level to zero when not registering any talking, then when you suddenly say something and you are not too loud the phone doesn't seem to pick it up right away, not sure what that function is called... maybe its asterisk that does it if set to 'pass silence' along when people don't talk during call to save bandwidth? Its usually felt most on hands free calls when you are farther away from the phone.