Okay, equipment used: Linksys SPA922-series phones Windows 2003 Server behind Firewall NOT using STUN, we use a SIP ALG on an Edgewater Edgemarc Router, which acts as proxy. This is how I run our QOS and traffic shaping. Thus, under "Providers and Gateways" in the 3cx menus, the router is listed as the provider. So here's the deal. If I select unconditional call forwarding in the admin menu, I can forward a call from an internal extension to an external cellular phone. This is the flow: Outside Cell--> DID --> DID on 3cx mapped to Extension 218 --> Extension 218 unconditional forward to 9-801-555-xxxx --> Call forwards correctly to 9-801-555-xxx The above scenario works correctly. Unfortunately, it's annoying for me, as I don't want to have to deal with forwarding salespeople's calls anytime they're out of the office. There is currently no functionality in 3cx Call Assistant to handle this, either, unless I want to set the extension to forward to a cell number when the phone status is set to away. So what I'd like to do is have people able to set the call forwarding at their phone stations. The Linksys SPA922 supports this. Unfortunately, I get an error anytime I enable forwarding at the phones rather than at the 3cx extension admin menu. Here's the flow: Outside Cell --> DID --> DID on 3cx mapped to Extension 218 --> Extension 218 is available --> Call transfers to Extension 218 --> Extension 218 attempts to forwards call --> Call does not forward --> Call transfers to Extension 218 Voicemail --> Call ends. Here's the log: 13:30:20.625 Endpoint::findSource [CM010001] Line configuration does not allow identification of the source of this call. Check Advanced Options for Gateways and Providers and match a field to a correct value from the following: Contact IP: '192.168.0.12'; From: '8014002997'; To: '218'; Rline: '318'; Contact: '8014002997' 13:30:20.546 MediaServerReporting::STUN [MS101003] Call(1245) Ln:10019@Veracity: Possible firewall problem. Address mapping failed on STUN server 192.168.0.12:3478 for local address ":9010" 13:30:20.546 CallConf:nIncoming [CM103002] Call(1245): Incoming call from 80140029xx (Ln:10019@Veracity) to sip:email@example.com:5060 Above, I'm simply trying to forward the call to another extension. That's not working either. Any suggestions?