est-Line: INVITE hp:0291970552030.253.253.71:506 SIP/2.0 Message Header via: SIP/2.0/UDF 30.30.10.32:5060;branch=z9hG4bK2117399041 From: 0291970550 sip:0291970550030.253.253.71:5060>; tag=1606844216 TO: <sip:0291970552030.253.253.71:5060> call-ID: 1362148818 CSeq: 21 INVITE Contact: 30.10. 32 :5060> Status-Line: SIP/2.0 300 Multiple choices Message Header via: SIP/2.0/UDP 30.30.10. 32:5060: received=30. From: "0291970550" <sip:0291970550030.253.253.71:5060>;tag=1606844216 To: sip:0291970552030.253.253.71:5060>;tag-2aa9200040d10bc6dbd109bd2077ae46d224266ad1 Call-ID: 1362148818 CSeq: 21 INVITE Contact: <sip:0291970552030.253.253.68: Content-Length: 0 Request-Line: ACK Hip:0291970552030.253.253.71:5060 SIP/2.0 Message Header via: SIP/2.0/UDP 0.10 32:5060;branch=z9hG4bK2117399041 From: "0291970550"<sip:0291970550030.253.253.71:5060>;tag-1606844216. TO: <sip:0291970552030.253.253.71:5060>;tag=2aa9200040d10bc6dbd109bd2077ae46d224266ad1 call-ID: 1362148818 CSeq: 21 ACK Content-Length: 0 FIGURE 8.16 Wireshark analysis: SUT in the CALLING state receives a "300 Multiple Choices" message, the generated ACK must respect the test specifications. 8.4.4.3 Timers Test Some ETSI TPs aimat verifying the correct management of timers in retrans- missions of messages or state transitions when there are no responses. For example, if an unreliable transport (UDP) is used, it should be verified that the IUT, when an INVITE client transaction is in the calling state, it repeats its INVITE request on the timeout condition of timer A, which has been initially set to a value of T1. 8.4.5 Robustness Tests A torture test is an evaluation of the SIP IUT ability to withstand extreme conditions. The following treatment reports some example, derived from RFC 4475, useful to stress the considered INVITE client transaction. For example the 200 success response to the INVITE sent by the IUT could be a 200 message with "unusual reason phrase" as reported previously in Figure 8.9 or with an "empty reason phrase" In fact, a 200 response containing no r