There are several reasons: 1) you are trying to impersonate someone else which we don't like. (Or possibly someone else is trying to impersonate you). If we permitted digestusername "dheeraj" to manipulate contacts of AOR &quot;san(a)iptel.org&quot;.org", that would be a real security pain. # U 2003/12/20 07:07:02.039699 202.54.98.63:10131 -> 195.37.77.101:5060 REGISTER sip:iptel.org SIP/2.0. Via: SIP/2.0/UDP 202.54.98.63:5060. From: sip:san@iptel.org. To: sip:san@iptel.org. Call-ID: 00075012-14e60350-64ceec11-054fc72d(a)202.54.98.63. CSeq: 102 REGISTER. User-Agent: CSCO/5. Contact: <sip:san@202.54.98.63:5060>.Authorization: Digest username="dheeraj",realm="iptel.org",uri="sip:iptel.org",response="78627be55d4c2912675be0d29f99cd96",nonce="3fe3e831e2daf98432cbc4ca1dc8a6c73849fda5",algorithm=md5. Content-Length: 0. Expires: 3600. . # U 2003/12/20 07:07:02.041306 195.37.77.101:5060 -> 202.54.98.63:5060 SIP/2.0 403 That is ugly -- use To=id in REGISTERs. Via: SIP/2.0/UDP 202.54.98.63:5060. From: sip:san@iptel.org. To: sip:san@iptel.org;tag=794fe65c16edfdf45da4fc39a5d2867c.8e59.Call-ID: 00075012-14e60350-64ceec11-054fc72d(a)202.54.98.63. CSeq: 102 REGISTER. Server: Sip EXpress router (0.8.12-tcp_nonb (i386/linux)). Content-Length: 0.Warning: 392 195.37.77.101:5060 "Noisy feedback tells: pid=22929 req_src_ip=202.54.98.63 req_src_port=10131 in_uri=sip:iptel.org out_uri=sip:iptel.org via_cnt==1". 2) we don't accept requests with IP addresses in r-uris as opposed to DNS names. We don't like them either. Use names. U 2003/12/20 15:58:39.878330 195.37.77.101:5060 -> 24.7.100.83:5060 SIP/2.0 403 Use domain name in SIP -- we deny IP addresses -- sorry. I suspect both error messages are pretty self-explanatory -- what is the problem? -jiri At 12:35 PM 12/20/2003, Santosh Subramanian, Noida wrote: -- Jiri Kuthan http://iptel.org/~jiri/