[Freeswitch-dev] FreeSwitch + ISDN + analog phone adapters - status

Jan Berger janvb at live.com
Fri Jan 30 07:30:21 PST 2009

hi Hans,
The standard for a PABX on G.711 is 6ms packaging of data - this is 48 byte per channel. If you go higher than this you start getting to much latency, if you go lower than this you start using to much CPU.
400 byte is 50ms, meaning we have spent a lot of the latency budget already here, but this shoud be run-time configurable per channel as per need.
- G.711 6 ms
- IVR is 250 ms
- 729 10 ms
- 723 30 ms
You need to take into consideration that you are on a system with 8, 16 or 32 E1's of whick some is running IVR, others SIP, others swicthing back out on a different E1 etc.
> > Also I have thought through message timing. In bigger systems I see that it is > required to dither messages in time. On cannot simply receive 30x400 bytes on > an E1 and burst it into the system, because the message queues will overflow > pretty quickly. Instead the interrupt rate of the hardware needs to be > increased so that 400 bytes are received in "1/30 * interval" fashion. This > will generally improve the system and load-balance in time.> > > The generic Message Header looks like this:> > /* NOTE: All fields are little endian */> > struct zap_hdr {> uint8_t dwDstNode[4]; /* Destination Node */> uint8_t dwSrcNode[4]; /* Source Node */> uint8_t wCommand[2]; /* Command Number */> uint8_t wMsgNum[2]; /* Message Number */> uint8_t bReserved[4]; /* Reserved bytes */> };> > If you have access to ISDN testing equipment and would like to help test the > non-EuroISDN variants of my upcoming ISDN implementation, please let me know.> > I expect to have something up and running within the next month, hopefully not > running out of time this time :-)> > --HPS> > _______________________________________________> Freeswitch-dev mailing list> Freeswitch-dev at lists.freeswitch.org> http://lists.freeswitch.org/mailman/listinfo/freeswitch-dev> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-dev> http://www.freeswitch.org
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