[Asterisk-Dev] // how to find clue from zaptel drives about the below topic.

dev2003 at 126.com dev2003 at 126.com
Tue Jun 14 06:25:31 MST 2005


can  anyone help me to give me some clue about this 

The Zaptel Architecture and PRI Library Overview


Background of Zaptel - where it came from, what motivated it, etc. 
What Zaptel is and what it does: DTMF/MF generation, Echo Can, Analog/Digital line signaling framework, internationalization - tones, etc, hooks into HDLC, Timing - 1000hz telephony timing - good for mixing audio streams, Conferencing and of course Pulse dialing/detection 
What it doesn't do: support for cards w/ dsps that do things such as DTMF detection, codecs, etc. 
Where it could go: Hooks for DTMF detection hardware hardware.. 
A bit about Zaptel Drivers: What kind of hardware can be zaptel hardware? Anything that you can pull an audio stream from. Asterisk/Zaptel does the rest - Ex. USB phone, 
Hooks into framework: Data Tx/Rx, Signal Bits - hookstate information, etc 
What exactly is a PRI? 23 bchannels (voice) and 1 dchannel (data/signalling). Where does libpri fit in? What is Q.921 protocol implementation and the higher Q.931 messaging layer. 
What kinds of switches does it support? NI2, NI1, AT&T 5ESS, 4ESS, DMS100, EuroISDN, GR303 (Not quite PRI, but similar in signalling), Q.SIG - PRI on steroids 
What direction is it taking? Supplementary Services - Q.SIG features, Two B-channel Transfer (passing a locally bridged call back into the network)m Calling name over facility IE, Advice of Charge - CDR support(?) (Cost of call data)m Call Diversion Metadata (redirecting name, number, reason, originally called name, number, etc), Message Waiting Indication (Yep, there's a version for PRI too :-) ) 
What's the Next Step for Zaptel and LibPRI? There is a LOT of call related information that is passed over facility IEs in Q.SIG and other protocols. Support for these routines would give libpri better grounds 
Other ideas to be further developed if time permits:
Zaptel/libpri/chan_zap profiling and performance testing (How many SETUPs per second, etc )


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