[SR-Users] Swap of From and To - kamailio 3.1.x problem?

Hi I have a problem which pops up occasionally. My scenario is a kamailio 3.0.x server coupled with SEMS 1.2.1 Calls go to SEMS and occasionally it will issue a refer to the caller (an SPA962 linksys) The problem is that the refer seems to get screwed up somewhere and the referred call changes the From field to the To field - in this case 711. The problems start below at 15:58:21 after the refer I'd like to know if this is a problem with Kamailio or a problem with the phone. The call fails on the SEMS_SEND section when the From field is validated. I suspect the phone is the culprit, but external advice appreciated. I'm not quite sure what the s_xxx call id means? Here is the log Dec 24 15:58:20 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: f43507d4-e02f109b(a)10.1.39.192 (New request) Method:<REFER> r-uri <sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08> To: sip:711@joondalup.fesa.sto From: sip:902@fesa.sto Dec 24 15:58:20 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: f43507d4-e02f109b(a)10.1.39.192 ( reply etc ) Method:<REFER> r-uri <sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08> To: sip:711@joondalup.fesa.sto From: sip:902@fesa.sto Dec 24 15:58:20 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: f43507d4-e02f109b(a)10.1.39.192 (Loose route) Method:<REFER> r-uri <sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08> To: sip:711@joondalup.fesa.sto From: sip:902@fesa.sto Dec 24 15:58:20 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: f43507d4-e02f109b(a)10.1.39.192 (RELAY, start of processing) Method:<REFER> r-uri <sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08> To: sip:711@joondalup.fesa.sto From: sip:902@fesa.sto Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: s_275259592d_358d20ea49bf (New request) Method:<INVITE> r-uri <sip:7020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08 Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: s_275259592d_358d20ea49bf (handle initial request) Method:<INVITE> r-uri <sip:7020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08 Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: s_275259592d_358d20ea49bf (t_check_trans) Method:<INVITE> r-uri <sip:7020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08 Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: s_275259592d_358d20ea49bf (Request For Me) Method:<INVITE> r-uri <sip:7020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08 Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: s_275259592d_358d20ea49bf (SEMS, rewrites) Method:<INVITE> r-uri <sip:020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08 Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[399]: WARNING: <script>: s_275259592d_358d20ea49bf (SEMS_SEND) Method:<INVITE> r-uri <sip:020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08 Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[398]: WARNING: <script>: s_275259592d_358d20ea49bf (SEMS_SEND_REPLY) Method:<INVITE> Status:<603> Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[398]: CRITICAL: <script>: s_275259592d_358d20ea49bf (SEMS_SEND_FAIL) Method:<INVITE> Status:<<null>> Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[404]: WARNING: <script>: s_275259592d_358d20ea49bf (New request) Method:<ACK> r-uri <sip:7020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08 Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[404]: WARNING: <script>: s_275259592d_358d20ea49bf ( reply etc ) Method:<ACK> r-uri <sip:7020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08 Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[404]: WARNING: <script>: s_275259592d_358d20ea49bf (Not a loose route) Method:<ACK> r-uri <sip:7020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08 Dec 24 15:58:21 mc0 /usr/local/sbin/kamailio[404]: WARNING: <script>: s_275259592d_358d20ea49bf (ACK in lr) Method:<ACK> r-uri <sip:7020@fesa.sto> To: sip:7020@fesa.sto From: sip:711@10.50.20.10:5070;LINEID=fac9f6b7cb08