[asterisk-users] Problem with incoming and outgoing calls via TDM

[Gordon Henderson]

On Wed, 11 Mar 2009, Rosa De Santis wrote:

>
> Hello all.
>
> Please, I'd like to know if somebody can help me with this problem.
> I have successfully configured a PBX with Asterisk 1.4 and a Digium analog card with 4 ports.
>
> This PBX has a lot of incoming and outgoing calls, and works perfect in 
> general, but there are some extrange cases where an incoming call is 
> bridget with an outgoing call, and the caller that is calling TO the PBX 
> can even hear the dtmf tones of the caller that is calling OUT the PBX, 
> and due the high traffic this is happening a lot. It seems that asterisk 
> is taking the zap channel to call out in the exact moment before it is 
> marked as busy with the incoming call. Please, is there any 
> configuration to avoid this?

It's called "glare" and your options to "fix" it partly depend on what 
country you are in. I don't think it's totally fixable with analogue 
lines.

Make sure you have the right country code specified in /etc/zaptel.conf 
and are using "Kewlstart". Eg. for the UK:

fxsks=1
fxsks=2
fxsks=3
fxsks=4
loadzone=uk
defaultzone=uk

Your options are to replace the 'ks' with 'gs' or 'ls' - but others might 
be able to advise you what's best for your country/telco.

But do make sure your incoming calls start at one end, and outgoing start 
at the other - so if the first line is connected to port 1, 2nd to port 2, 
etc. you want to dial-out starting at port 4 - that's the capital G option 
in dial - eg. dial(Zap/G1/xxxx...) the lower-case g will start outbound 
dialing at the lower port number. (And put the lines in the right group in 
/etc/asterisk/zapata.conf)

Another solution might be to get more channels - are your users & callers 
complaining of busy tones?

Gordon