asterisk users - Feb 2008 - Simultaneous Inbound and Outbound calls on analog lines...

Hello! I've run into a problem where a user is making an outbound call at
the same time that an inbound call is being made on the same analog line. It
appears that as the zap channel is opened for the outbound call, it is simply
answering the inbound call. Obviously, both parties involved in the calling get
a bit confused. Previously, it happened only on an occasional basis. However, as
this installation gets more and more use, we are finding it happens more often.
How can this situation be prevented? Shouldn't zaptel see an incoming call
and simply choose another trunk? We are running Asterisk 1.2.12.1 and Zaptel
1.2.22.1. Any ideas?!?

Tim Nelson
Systems/Network Support
Rockbochs Inc.

This is called glare. What you should do is reverse your outbound hunt. If you
dial zap/g0 simply use zap/G0. The capitol G makes the line go 5 4 3 2 1 instead
of 1 2 3 4 5. You may still see glare but this usually reduces it.
James Finstrom
Rhino Equipment Corp.
http://www.rhinoequipment.com

-----Original Message-----
From: Tim Nelson <tnelson at rockbochs.com>

Date: Wed, 27 Feb 2008 14:55:49 
To:Asterisk Users Mailing List - Non-Commercial Discussion<asterisk-users at
lists.digium.com>
Subject: [asterisk-users] Simultaneous Inbound and Outbound calls on analog
	lines...


Hello! I've run into a problem where a user is making an outbound call at
the same time that an inbound call is being made on the same analog line. It
appears that as the zap channel is opened for the outbound call, it is simply
answering the inbound call. Obviously, both parties involved in the calling get
a bit confused. Previously, it happened only on an occasional basis. However, as
this installation gets more and more use, we are finding it happens more often.
How can this situation be prevented? Shouldn't zaptel see an incoming call
and simply choose another trunk? We are running Asterisk 1.2.12.1 and Zaptel
1.2.22.1. Any ideas?!?

Tim Nelson
Systems/Network Support
Rockbochs Inc.


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This is a well know issue in analogue trunks, called collisions or
glare. As you say, more is the traffic more are probability of
collisions. One trick to reduce this problem is to reverse the outgoing
hunting group against the incoming hunt group.

Jorge Mendoza

Tim Nelson wrote:
> Hello! I've run into a problem where a user is making an outbound call
at the same time that an inbound call is being made on the same analog line. It
appears that as the zap channel is opened for the outbound call, it is simply
answering the inbound call. Obviously, both parties involved in the calling get
a bit confused. Previously, it happened only on an occasional basis. However, as
this installation gets more and more use, we are finding it happens more often.
How can this situation be prevented? Shouldn't zaptel see an incoming call
and simply choose another trunk? We are running Asterisk 1.2.12.1 and Zaptel
1.2.22.1. Any ideas?!?
>
> Tim Nelson
> Systems/Network Support
> Rockbochs Inc.
>
>
> _______________________________________________
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>
> asterisk-users mailing list
> To UNSUBSCRIBE or update options visit:
>    http://lists.digium.com/mailman/listinfo/asterisk-users
>

In the telephony world, this is called glare, it's most prevalent on  
Analog (though you can have the same thing happen with robbed-bit  
T1).  There really isn't much you can do to prevent it, only minimize  
it.  You need to have your inbound and outbound starting at opposite  
ends.  If your incoming calls are coming top down, then you need to  
use G<your group number> in your Dial app so that outbound calls go  
bottom up, or vice versa.

HTH,

James Texter

On Feb 27, 2008, at 2:55 PM, Tim Nelson wrote:
> Hello! I've run into a problem where a user is making an outbound  
> call at the same time that an inbound call is being made on the same  
> analog line. It appears that as the zap channel is opened for the  
> outbound call, it is simply answering the inbound call. Obviously,  
> both parties involved in the calling get a bit confused. Previously,  
> it happened only on an occasional basis. However, as this  
> installation gets more and more use, we are finding it happens more  
> often. How can this situation be prevented? Shouldn't zaptel see an  
> incoming call and simply choose another trunk? We are running  
> Asterisk 1.2.12.1 and Zaptel 1.2.22.1. Any ideas?!?
>
> Tim Nelson
> Systems/Network Support
> Rockbochs Inc.
>
>
> _______________________________________________
> -- Bandwidth and Colocation Provided by http://www.api-digital.com --
>
> asterisk-users mailing list
> To UNSUBSCRIBE or update options visit:
>   http://lists.digium.com/mailman/listinfo/asterisk-users