Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Gonzalo Camarillo ASRL Advanced Signalling Research Lab. SIP / ISUP interconnection

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Telephone Services GSTN (General Switched Telephone Network) IP Telephony GSTN

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Brief SS7 introduction (architecture) Gateway architecture ( SG, MGC, MG ) Contents ISUP - SIP interworking issues and proposed solutions

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Different architectures GSTN architecture: Intelligence in the network Dumb terminals SIP architecture: Move the intelligence to the edge

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 DSS 1ISUPDSS 1 Signalling in GSTN Signalling in the network (between switches) User to network signalling

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 DSS-1 Q. 931 Protocol between the user and the network Much simpler than ISUP. Q. 921 Handles the transport of the messages

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Signalling in GSTN SS7 (System Signalling No. 7)

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 General ISUP SIP Conversion SG SIP Client SIP Server STP ISUP/MTP E1/T1 SIP SS7 Voice Stream Signalling MG RTP MGCP SIP IP network ISUP/IP MGC DSS 1

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Architecture of the distributed gateway Signalling Gateway Media Gateway Controller Media Gateway GSTN side IP side Voice stream ISUP SIP MGCP ISUP/IP

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Signalling Gateway To find the appropriate media gateway controller Function: Signalling GW ISUP/IP ISUP SIPMGCPSIPMGCPSIPMGCPSIPMGCP MGC

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Media Gateway Mapping between different voice formats Control Protocol GSTNRTP

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Media Gateway Controller for distributed Media Gateways Actual mapping between protocols (ISUP-SIP) Control the Media Gateway/s Authentication, Authorization and Accounting (AAA) Functions

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Experiences implementing ISUP to SIP mapping Different flavours of ISUP (message flow) Overlap signalling (SAMs) In band announcements and ring-back tone ISUP transparency Billing in forwarding situations Tracing calls (malicious, SOS)

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 ITU ISUP message exchange during a call Different message flows ANSI ISUP: CPG before ACM

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Overlap signalling (SAMs) European phone numbers does not have a fixed length. Example: Finland Helsinki Ericsson Front desk Finland Helsinki Ericsson Camarillo’s The ingress gateway cannot know when the number is complete.

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Proposed solution Ingress gateway waits for SAMs with more digits a certain amount of time. Timer = 0 Heavy signalling traffic may be generated Timer = 5 secs ( inter-digit timeout) User is not that patient

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 In-band announcements and ring-back tones ‘Your call is being forwarded to an automatic voice mail’ Ring-back tone Busy tone SIP Client E1/T1 MG RTP DSS 1 Proposed solution: 183 SIP response

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 ISUP transparency (SIP bridging) IP network ISUP/MTP E1/T1 Voice Stream Signalling STP SIP RTP ISUP/MTP E1/T1 STP SG MG MGC MGCP ISUP/IP

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 ISUP transparecy ( SIP bridging) ISUP messages in SIP bodies (MIME), SIP INFO method, reliable 1xx responses... Trusted parties, confidentiality, ISUP flavours...

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Billing scenarious Isabel calls from Spain to my GSM mobile: (Finland’s international prefix) Isabel pays the call leg Spain-Finland I pay the call leg Finland-Atlanta SIP is end to end … where are the call legs??

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Tracing calls SOS services ( physically closest center ) Malicious calls An IP address or a SIP URL do not give any useful information for catching the “bad guys”.

Advanced Signalling Research Lab. Fall ‘99 VON VON protocols - SIP Gonzalo Camarillo Atlanta September 28th, 1999 Further information draft-ietf-sigtran-mime-isup-00.txt draft-ietf-mmusic-sip-multipart-00.txt draft-zimmerer-mmusic-sip-isup-mime-00.txt draft-ietf-mmusic-sip-info-method-01.txt draft-ietf-mmusic-sip-100rel-00.txt draft-roach-mmusic-sip-provisional-media-00.txt draft-donovan-mmusic txt draft-roach-mmusic-sip-pstn-require-header-00.txt draf-zimmerer-mmusic-sip-bcp-t-00.txt draft-roach-sip-isup-parameters-00.txt draft-camarillo-mmusic-sip-isup-bcp.txt IETF internet drafts ( )