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Fax noice tone on ip phoness

Hi all,

i have got an issue .. i configured IP Phones for one of my customer .. they have one PRI .. whn some one call to those ip phones from outside,some time they hear tone like Fax tone or tone like internet is connectd and some time they can call without any problem .. so how should i trouble shoot this issue !! can any one help me ... i gues this would be issue from service provider but how can i make it sure from my side !!!!


5 Replies 5

paolo bevilacqua
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dial-peer voice pots 1

incoming called-number .


also, do you have isdn overlap in your contry? Make sure to put it under interface.

thanks for your reply bevilacqua !! im not using H.323 on my gateway im using MGCP !! i dont think so this dial peer will be beneficial !! any alternate solution !!!


Hi Ahmed,

There may be a problem for a single B channel.

To troubleshoot, I would go down, testing each b channel. Use "show voice call summary" to find out which channel you're on. If you have multiple active calls it will be harder, but "show call active voice brief" can help.

There are two methods to do this:

1) The easiest way is to place a call, test the channel, and place it on hold. The next call will be on the next available channel

2) Place a call, and when you've tested a channel use this command:

interface Serial0/0/0:23

isdn busy b_channel

When you have it determined down to see if it's a single b channel or not, it will be much easier to get the provider involved and find out if it's your equipment or the provider. I think there's a slightly better chance it's on the gateway.



Hi nic,

Thanks for your rply and sory for my late reply bcoz i got ill so didnt able to check forum !!!

I will do this testing by tomorow and will update you thanks & sorry again ..


Hi nic,

today i got the problem solved ... actually problem was from service provider side .. thy have fixed it out from there side ....


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