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If call preservation were enabled for the call then the phone would
stay offhook until the user initiated a disconnect. This leads me to 2
thoughts:<br>
<br>
1. The call does not have call preservation enabled to begin with. If
this is true then as soon as the phone loses CM registration it will
clear the call. This is possible depending on the type of call
(conference, transfer, mtp, internal, external) and the signaling
protocols involved in the call (h323,cti call preservation disabled by
default. h323 can be enabled with service parameter). Possibly the
easiest way to verify this is to setup a call between 2 phones in india
and then flap the WAN connection. The call should stay up as SCCP
endpoints always have call preservation enabled. The most likely
culprit here is the gateway signaling protocol. If h.323 then change CM
service parameter/enterprise parameter to enable h.323 call
preservation.<br>
<br>
2. If call preservation is enabled and the call still automatically
clears I only know of 1 thing that would cause this - ICMP messages on
the network. Gateways and phones both look for ICMP unreachable
messages and terminate preserved calls if a threshold number of ICMP
messages are received. When your WAN flaps does it flap in such a way
that the endpoints (gateway,phone) would receive ICMP messages? I do
not know of any way to change the ICMP behavior on endpoints. However,
you could creative in the network and have ICMPs suppressed for RTP
streams. This would allow the endpoints to continue to preserve the
call. Be careful though, this can also lead to orphaned call legs.<br>
<br>
While these may be technically viable what are the chances your
external callers and users will hang on the line through 10 seconds of
no audio?<br>
<br>
/Wes<br>
<br>
On Thursday, May 28, 2009 9:06:31 AM, Aman Chugh
<a class="moz-txt-link-rfc2396E" href="mailto:aman.chugh@gmail.com"><aman.chugh@gmail.com></a> wrote:<br>
<blockquote
cite="mid:d4c697ad0905280606p77566f10rfe063b16ad510cda@mail.gmail.com"
type="cite"><br>
I have a remote location which registers to the CCM at the central site
, all the PSTN traffic exits out of the central site gateway and we do
not have any PSTN link at this remote site. This site is an extension
of my central site. I have situation here as the my data link to this
site flaps for 10 seconds resulting in all active calls to drop. <br>
<br>
I am using CCM 6 at the central site. Is there any way I can keep the
call up when the link flaps. I know the call survives only when IP
Phone losses it's link with CCM but in my case the entire data link
goes down. <br>
<br>
I know it is not possible as the entire data link goes down but out of
curiosity want to know if this is remotely possible.<br>
<br>
TIA,<br>
Aman<br>
<pre wrap="">
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