RTMMoIP Alfredo Terzoli / Mosioua Tsietsi

PLAN: tiding up… ENUM: a few more wordsENUM: a few more words B/W calculation for VoIPB/W calculation for VoIP Plan for the rest of the weekPlan for the rest of the week

“Call setup” PSTN to VoIP Call via SIP Sip Query e164.arpa.? Dial DNS-Server Sip serverGateway Response (slide by Steven D. Lind,AT&T)

VoIP via SIP to VoIP DNS-Server “ENUM” SIP-Server Gateway

ENUM ‘strange’ format… My telephone at home in ENUM format:My telephone at home in ENUM format: e164.arpa Why not (it seems more logical!):Why not (it seems more logical!): e164.arpa e164.arpa

ENUM ‘strange’ format The second way of representing makes explicit in the DNS search the current format of e.164, which might change in futureThe second way of representing makes explicit in the DNS search the current format of e.164, which might change in future Using the first one (fully dotted), we isolate ENUM from changes in the e.164 format by the ITU. The only assumption is that e.164 will be numbers, which is safeUsing the first one (fully dotted), we isolate ENUM from changes in the e.164 format by the ITU. The only assumption is that e.164 will be numbers, which is safe

A conversation becomes DATA

And it is tranported…

Another view!

VoIP bandwith calculation Let’s get more specific on B/W usage, for AUDIO transmissionLet’s get more specific on B/W usage, for AUDIO transmission Two families of CODECS:Two families of CODECS: – wave coding unrestricted, any sound (sound engineering)unrestricted, any sound (sound engineering) – vocoding good for voice, can reach very low bitratesgood for voice, can reach very low bitrates kbps: kilo bits per second (here kilo=1000, not 1024!)kbps: kilo bits per second (here kilo=1000, not 1024!)

‘Vocoders’ for Videos?

Voice Synthesisers & Vocoders A voice synthesiser includes a vocoder of some type, naturallyA voice synthesiser includes a vocoder of some type, naturally In fact, using a voice synthesiser one can substantially reduce the bandwidth needed for the transmission of voice. HOW?In fact, using a voice synthesiser one can substantially reduce the bandwidth needed for the transmission of voice. HOW? (BTW, who knows how MIDI works?)(BTW, who knows how MIDI works?)

B/W consumption of a few codecs

VoIP bandwith calculation

Bandwidth calculators at:Bandwidth calculators at: – bandwidth-calculator.html bandwidth-calculator.htmlhttp:// bandwidth-calculator.html (btw, the white paper distributed to you on b/w calculation comes from newport- networks) (btw, the white paper distributed to you on b/w calculation comes from newport- networks) – calc.html calc.htmlhttp:// calc.html

Reducing overhead cRTP compact RTP (RFC 2508):cRTP compact RTP (RFC 2508): –From 40 to 2 to 4 bytes, substantial Trunking: same packet transport more than one conversation (of course, can be used only if on a trunk)Trunking: same packet transport more than one conversation (of course, can be used only if on a trunk)

Main Prac Building a service in AsteriskBuilding a service in Asterisk Possible dates:Possible dates: –WEDNESDA 16s: presentation of your idea –TUESDAY 29: demo of the implemented service

A few URLs to follow (by Friday) _vs_skype (blog with comparison of skype and googletalk) _vs_skype (broadband providers VoIP dilemma) / (broadband providers VoIP dilemma) / &name=News&file=article&sid=170&newlang =eng (P2P SIP) &name=News&file=article&sid=170&newlang =eng (P2P SIP) &name=News&file=article&sid=170&newlang =enghttp://voxilla.com/modules.php?op=modload &name=News&file=article&sid=170&newlang =eng

Questions?