asterisk users - Jul 2008 - line goes silent for a few seconds at the start of outgoing calls

Hi there,

I am experiencing a strange problem and am looking for advice to
where to start looking. Or any clues, really.

I have Asterisk running on our router, and it is configured to
forward calls to a provider out there (who is also using Asterisk).
On the inside of the Asterisk are several voip clients, among which
a Siemens C450ip.

If that phone makes a call, there's a few seconds right after the
peer picks up when neither side can hear the other; after a few
seconds, everything works.

This only happens if that phone calls an outside phone via that
provider; I cannot reproduce it from another phone via the same
provider, nor if the Siemens phone is routed via a different
provider. Also, internal calls and incoming calls via the provider
to the Siemens are fine.

I tried debugging but I could not find any hints. I am led to
believe that there is some codec stuff going on, but I cannot figure
out what, especially since my Asterisk does canreinvite=no, so the
codecs are negotiated between my Asterisk and the phone and my
Asterisk and the provider independently.

Yet, it needs the Siemens on one side of the Asterisk, and this
specific provider on the other side for the problem to appear.

What's going on? How can I fix this? Where should I look?

Thanks,

-- 
martin;              (greetings from the heart of the sun.)
  \____ echo mailto: !#^."<*>"|tr "<*> mailto:"
net at madduck
 
"with sufficient thrust, pigs fly just fine. however, this is not
 necessarily a good idea. it is hard to be sure where they are going
 to land, and it could be dangerous sitting under them as they fly
 overhead."
                                                           -- rfc 1925
 
spamtraps: madduck.bogus at madduck.net
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