I just got myself a nice cheap SIP phone. For some reason, it’s acting really funky. I set up an SIP extension for it in Asterisk admin, and configured the phone correctly. The phone logs in okay, pulls an IP from the DHCP server, and authenticates to the Asterisk server okay. It recognized when there was new voicemail, etc. However, for some reason, whenever I try to call that phone, Asterisk tells me that the user is on the phone. When I try to dial other extensions from this phone, it gives me a busy tone. I can’t figure out what’s wrong.