Business Phone Systems

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#573761 06/25/14 03:25 PM
Joined: Jun 2004
Posts: 1,367
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Joined: Jun 2004
Posts: 1,367
I have a weird one here that I am a bit stuck on.

First, I haven;t sat down to figure out the correct way for SIP trunks to register using an IP address instead of a name. I put in the IP in 10-29-06 and uncheck DNS mode, but they seem to fail to register. It could be something else, but want to verify that that should work.

Here is the problem:
phone system is on network with gateway of .1 which is a cisco ASA. A rule is built directing all traffic to and from the SIP provider's IP to use Gateway .251 on the same network.

System goes to communicate withthe URL of the SIP provider and sends out a name query. The customer does not have an onsite DNS server. I port mirrored the port the system is on and see the DNS query but I never see a response.
This happens regardless of the DNS server I put in.
HOWEVER, it DOES SOMETIMES work and I see an immediate response.
When it does work the call goes out normally, when it doesn't the call will grab a trunk, then sit there for up to 30 seconds before proceeding.

Naturally I don't have access to the cisco, and their IT guy says everything is working as it should.
I can sit there and and have my queries from the laptop on the same network get reponded to immediately.

An additional quark is remote VOIP phones are havingf intermittant registering issues. they are going across a VPN to the main site. If I have several phones at a remote site a few will register just fine, but a few will never find the system. These were working before the rule was put into place. If I reset a phone after it registers it may re-register right awayor it may take up to 10 resets to reregister.

If I point the system to use the .251 gateway, call go out fine, but then the remote phones can't talk to the system

Last edited by BillFlippen; 06/25/14 03:28 PM.

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If you haven't already get a small switch with mirroring capabilities, lap top with Wireshark.
NTAC using the Wireshark data will nail down the issue.

After the VoIP phones register do they stay up or are they dropping periodically? If dropping, Wireshark will show why.

We get old too soon, smart too late

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