T.38 Deployment Phases: Phase I, intra-enterprise: Phase II, SIP trunking: Phase III, tandem carriers: 2011+
And Now…Bring on The ITSPs & Carriers!
Separating the Issues
Voice Is Easy! Voice is generally the default Agree on a codec Enable the media stream Take care of jitter-buffer management Get rid of echo You’re done! Call set-up timing not critical.
Timing is everything. But in Fax…
FoIP…It’s About Time Computer-to-computer protocol (T.30) Synchronous modems Media stream, which begins in G.711, wants to be renegotiated and switched to T.38 Timing is everything!
Phase III: Tandem-Carrier- Based Fax
So…What about testing? Many networks are untested for FoIP. Many carriers have SBC, proxies, and gateways incorrectly configured. Excessive signaling delay remains undiagnosed. Routes change frequently
Some Results: In a recent broadcast test 200 out of 2000 calls had late-arriving T.38 re-Invites leading to fax failures.
Outbound to ITSP Remote off hook T.38 re-Invite
G.711 Audio Caller Callee Point of no return T.38 re-Invite here. Bye-bye fax. DIS
So… Can our industry respond effectively to these problems?
ENUM: Tells you where you want to go Convert E.164 numbers to DNS lookup Returns URI of user’s ENUM record Record contains info on all services HD voice is driver But what about fax? Used for IP-only routing
2012 Goal 2012 will be the year the global carriers finally begin the move to an all-IP network.