[Asterisk-Users] Clicks, pops and noise

[Rich Adamson]

> I've got a TE410p connected via T1 to four channel banks (2 FXO and 2 FXS), no PRIs.
> 
> Some users are complaining that they hear clicks and pops on the FXS lines, 
> generally when they pick up the phone it's noisy. This happens only after a 
> while, e.g. after a fresh restart of everything, all is fine but after some time 
> these noises start appearing. From what I've read on the list, this could be 
> down to frame slips or some problem due to synchronization.
> 
> Since there's no incoming PRI to sync to, this means everything needs to be 
> internally clocked. Could it be the internal clock source on the card has gone 
> wonky? Or is something else in the server screwing up the clock signal?
> 
> Anyone else experienced this when connecting four channel banks to the TE410?
> 
> Zaptel.conf:
> 
> span=1,0,0,esf,b8zs
> fxsks=1-24
> 
> span=2,0,0,esf,b8zs
> fxsks=25-48
> 
> span=3,0,0,esf,b8zs
> fxsls=49-72
> 
> span=4,0,0,esf,b8zs
> fxsls=73-96

Timing (or sync) has nothing to do with PRI's. All T1/E1 data links
of any type require sync.

All T1/E1 links have timing/sync included in their transmit leg and
there is no way for you to turn it off. Its part of the T1/E1 spec.

If you don't have any T1/E1 connections to the outside world, then
pick one channel bank and call it your official source of sync, and
change the above definitions to sync off that channel bank. On all
other channel banks, configure them to sync off the asterisk card.

If you do have a T1/E1 that comes from your telco/pstn network, use
it as the source of clock sync, and config all channel banks to sync
from asterisk.

Your clicks will go away.