[Asterisk-Users] ISDN Clock Source

[Rich Adamson]

> I apologise in advance if this is a silly question, as "legacy" 
> telephone technologies are really not my forte.
> 
> Is there an E1 card that can provide clock source? (E.g. Make my 
> asterisk server look like a telco to my legacy PBX system?).
> 
> What I am trying to achieve is the following:
> 
> 
> --ISDN-------| Asterisk |-------ISDN--------| Legacy PBX |--

All E1's and T1's have an embedded clock in the transmit side of
the circuit. There is no way to turn it off or on; its part of the
spec.

You choose whether you want to "use" the provided clocking when you 
configure the hardware on the end of the E1/T1. For zaptel cards,
see the examples in /etc/zaptel.conf.