I have a provider that in order to set outbound CID they want me to make sure that the From Header in the sip invite matches the caller ID while the contact header matches the registration info. For example. My phone number with my provider is 2125551212 which is also my username. I want caller ID to show up as 7185551212. The provider wants that the header should be like this: =====begin SIP Headers====Adding codec 0x4 (ulaw) to SDP Adding non-codec 0x1 (telephone-event) to SDP Reliably Transmitting (no NAT) to y.y.y.y:5060: INVITE sip:13475551212 at sipxx.sipprovider.com SIP/2.0 Via: SIP/2.0/UDP x.x.x.x:5060;branch=z9hG4bK7d87735f;rport From: "7185551212" <sip:7185551212 at sipxx.sipprovider.com>;tag=as56382d68 To: <sip:13475551212 at sipxx.sipprovider.com> Contact: <sip:2125551212 at x.x.x.x> Call-ID: 21292bde7c00298c2d74c9033bb02c3c at sipxx.sipprovider.com CSeq: 103 INVITE User-Agent: Asterisk PBX Max-Forwards: 70 Remote-Party-ID: "7185551212" <sip:7185551212 at sipxx.sipprovider.com>;privacy=off;screen=yes Authorization: Digest username="2125551212", realm="sip10.xchangetele.com", algorithm=MD5, uri="sip:13475551212 at sipxx.sipprovider.com", nonce="a718c5ddb60d", response="7beb31c547f1252dcb9bf10b593b64a5", opaque="", qop=auth, cnonce="514eefb9", nc=00000001 Date: Tue, 11 Aug 2009 23:51:06 GMT Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY P-Asserted-Identity: <sip:7185551212 at sipxx.sipprovider.com> Content-Type: application/sdp Content-Length: 220 ====End Sip Headers==== Is that possible? If yes how? TIA