[Serusers] Proxy-Authentication response changing?

The UA (Sipura SPA-2000) is changing it's response on the ACK... sip scenario : http://www.addaline.com/traces/t4_index.html Raw trace: http://www.addaline.com/traces/t4.w I note that the caller's initial (challenged) INVITE produces: Proxy-Authorization: Digest username="580009",realm="worldipphone.net",nonce="4166db96623abffd65eab0 fcdd4e8e40ed31f6cd",uri="sip: 580011(a)worldipphone.net&quot;,algorithm=MD5,response=&quot;57bf811fd90aa1d5f34e3b0 2e62740de" inside the SIP packets. I trace all of them, and they remain identical, until frame #70. Frame 70 (the ACK) sends: Proxy-Authorization: Digest username="580009",realm="worldipphone.net",nonce="4166db96623abffd65eab0 fcdd4e8e40ed31f6cd",uri="sip: 580011(a)worldipphone.net&quot;,algorithm=MD5,response=&quot;eef5a947b282f173c5e7057 29f017faf" My proxy is picking up the new response, and reporting: Oct 8 13:20:29 red ser[1192]: ACC: transaction answered: method=INVITE, i-uri=sip:580011@worldipphone.net, o-uri=sip:~wCYW7mQU9Hrodvm6PwcJODzkQ9n9vBx_U@198.212.169.240:5060, call_id=058240b057fefa358d78e2705d09baff, from=<sip:580009@worldipphone.net>;tag=b5fe1311, code=200, uid=580009, fromtag=b5fe1311, uid=580009, fromuri=sip:580009@worldipphone.net, fromuser=580009, fromdomain=worldipphone.net, to=<sip:580011@worldipphone.net>;tag=e203a620, totag=e203a620, touri=sip:580011@worldipphone.net, touser=580011, code=200, userpart=580011, domain=worldipphone.net Oct 8 13:20:29 red ser[1215]: check_username(): No authorized credentials found (error in scripts) Oct 8 13:20:29 red ser[1215]: check_username(): Call {www,proxy}_authorize before calling check_* function !Oct 8 13:20:29 red ser[1215]: worldipphone.net-403: time_t=1097259629 ^LINE=135 ^FILE=/usr/local/lib/ser/include/sergatewayob.pre ^call_id=058240b057fefa358d78e2705d09baff ^cseq=189334723 ^contact=<null> ^from=sip:580009@worldipphone.net ^fromtag=b5fe1311 ^to=sip:580011@worldipphone.net ^totag=e203a620 ^method=ACK ^ruri=580011(a)198.212.169.15;lr;ftag=b5fe1311 ^messageid=10075^remark=authentication mismatch Oct 8 13:20:29 red ser[1215]: Warning: sl_send_reply: I won't send a reply for ACK!! and it won't reply with an authorization error to an ACK packet...so the ball is dropped there. This is pretty weird. Why would the response change? ---greg Greg Fausak www.AddaBrand.com (US) 469-546-1265