[Asterisk-Users] zaphfc - hfc pci based ISDN card : point2point & DDI

Philipp von Klitzing klitzing at pool.informatik.rwth-aachen.de
Wed Jun 30 05:33:17 MST 2004


> It looks like there are three methods of using HFC-S based ISDN BRI
> cards with *. Capi (via capi.conf), zaphfc (via zapata.conf), and
> isdn4linux (via modem.conf). Why, and which one is better and for which
> reasons? 

i4l: Trouble with outgoing DTMF (not working), less ISDN features than 
chan_capi, known to be not very stable/reliable (?works only with HiSax 
cards?), reportedly messy code, issues with echo and latency

chan_capi: more features (early dial, call deflection, ISDN hold & 
retrieve etc), stable, comes with echosquelch, works only with cards that 
have CAPI driver support; far more popular among Asterisk users compared 
to isdn4linux; can't detect if another application outside Asterisk is 
already using a specific ISDN channel (?)

zaphfc: works only with HFC cards, can also be used in NT mode (so that 
you can connect an ISDN PBX or an ISDN phone to Asterisk), works as ZAP 
channel and thus comes along with all the usual ZAP features (echo 
cancellation, ZAP timer, but also ZapBarge etc)

chan_misdn: very new; needs misdn kernel module or kernel 2.6.x; not 
widely used (yet)

Cheers, Philipp

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