Noise on incoming calls from PSTN

[lavrunin]

Our CS1000 has been running fine for a number of years. Recently we have had random occurences of noise on incoming calls from the PSTN. I have not discerned any pattern but the noise is always with our receiving (listening). The other end does not have any noise. The noise is like a bunch of clicking sounds on top of the actual voice. On some occasions it is low enough that you can still finish the call, at other times it is so loud that you have to have the person recall and sometimes the noise is still there.
Does anyone have any idea of where to look to solve this problem. All our phones utiize VOIP and internal calls are completely clear.
Thanks

 

[RickyPone]

How are you connected to telco?

 

[lavrunin]

We have two PRI lines, one is used for incoming and the other for outgoing.

 

[RickyPone]

Use ld 36 and test all of the incoming.

 

[trvlr1]

Have the Telco do non intrusive tests on the PRI to see if they see issues, possibly with timing etc.

 

[bhassell2000]

are you getting any slips or errors on the PRIs when you look in the PBX?

Thanks,

Buddy

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