Which SIP message element is mapped to QSIG FACILITY messages being tunneled across a SIP trunk between two Cisco IOS gateways?
Click on the arrows to vote for the correct answerA. B. C. D. E.
Mapping of QSIG Message Elements to SIP Message Elements This section lists QSIG message elements and their associated SIP message elements when QSIG messages are tunneled over a SIP trunk.
" QSIG FACILITY/NOTIFY/INFO &lt;""&gt; SIP INFO - " QSIG SETUP &lt;""&gt; SIP INVITE - " QSIG ALERTING &lt;""&gt; SIP 180 RINGING - " QSIG PROGRESS &lt;""&gt; SIP 183 PROGRESS - " QSIG CONNECT &lt;""&gt; SIP 200 OK - " QSIG DISCONNECT &lt;""&gt; SIP BYE/CANCEL/4xx""6xx Response References: http://www.cisco.com/c/en/us/td/docs/ios/voice/sip/configuration/guide/15_0/sip_15_0_book/tunneling_qsig.html.
When tunnelling QSIG messages over a SIP trunk between two Cisco IOS gateways, the FACILITY message element is mapped to the SIP INFO message. Therefore, the correct answer is D. SIP INFO.
In a SIP trunk, SIP messages are exchanged between the Session Border Controllers (SBCs) or gateways of the service provider and the customer. However, in some cases, a customer may want to tunnel QSIG messages over the SIP trunk to support legacy PBX features or interoperate with non-SIP endpoints.
When QSIG messages are tunneled over a SIP trunk, the QSIG messages are encapsulated inside SIP messages. The SIP INFO message is commonly used to carry non-call-signaling information between endpoints in a SIP network. Thus, the SIP INFO message is used to carry QSIG messages in a SIP trunk.
In summary, when tunnelling QSIG messages over a SIP trunk between two Cisco IOS gateways, the FACILITY message element is mapped to the SIP INFO message.