I made a call from 3254102 to 2944093. I then tried to do a transfer to 3254107. IP addresses have been changed to protect the innocent. Here's the REFER that the phone at 2944093 sends directly to Asterisk: U 216.186.128.68:5060 -> 216.186.142.203:5060 REFER sip:3254102@216.186.142.203 SIP/2.0. Via: SIP/2.0/UDP 216.186.128.68;branch=z9hG4bKba3b074892377BD1. From: <sip:2944093@216.186.128.68>;tag=C06397B-C3C1D97A. To: "Test User" <sip:3254102@216.186.142.203>;tag=as33e7dd7c. CSeq: 2 REFER. Call-ID: 4053b9972e7851f455d9d16e7706d3f4@216.186.142.203. Contact: <sip:2944093@216.186.128.68>. User-Agent: PolycomSoundPointIP-SPIP_601-UA/1.6.3.0067. Refer-To: <sip:3254107@ipt.oneeighty.com;user=phone?Replaces=a13c692-349c9c70-7bd27d33%40172.31.99.4%3Bto-tag%3Das2a8d818b%3Bfrom-ta g%3D3DE1A6BE-7262B959>. Referred-By: <sip:2944093@216.186.128.68>. Max-Forwards: 70. Content-Length: 0. Asterisk then goes and complains: Mar 27 16:25:57 NOTICE[20511]: chan_sip.c:6734 get_refer_info: Supervised transfer requested, but unable to find callid 'a13c692-349c9c70-7bd27d33@172.31.99.4'. Both legs must reside on Asterisk box to transfer at this time. There's NAT going on here too. The phone's real IP address is 172.31.99.4. I'm not really sure what the problem is except that it works fine when there's no NAT involved. I can see the real IP address in the dialog. I wonder if that's what is confusing Asterisk? Doug.