jra at baylink.com
Guest
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 Posted: Thu Feb 28, 2008 9:59 am Post subject: [asterisk-users] Simultaneous Inbound and Outbound calls on |
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On Thu, Feb 28, 2008 at 08:47:37AM -0600, James Texter III wrote:
| Quote: | On Feb 27, 2008, at 2:55 PM, Tim Nelson wrote:
| Quote: | 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?!?
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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.
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And, to expand a bit, this comes from the fact that on analog (and I
guess RBT-1, though I hadn't realized it happened there), there is not
a 3-way handshake to open the channel; each end can open it
unilaterally. This leads to a race condition, and thus, 'glare'.
The *reliable* way to fix this is to go to PRI, if you can a) get it,
b) afford it, c) terminate it, and d) profit!!
Oh, sorry; that's Slashdot. Never mind. 
Cheers,
-- jra
--
Jay R. Ashworth Baylink jra at baylink.com
Designer The Things I Think RFC 2100
Ashworth & Associates http://baylink.pitas.com '87 e24
St Petersburg FL USA http://photo.imageinc.us +1 727 647 1274
Those who cast the vote decide nothing.
Those who count the vote decide everything.
-- (Joseph Stalin) |
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