Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

cisco 7920 ip phone noise static crackle

cisco 7920 ip phones (2)

firmware: 7920.4.0-03-02

hardware info 4.0

cisco 1242AG access point

System Software Version: 12.4(10b)JA3

cisco 2651XM router

IOS: c2600-adventerprisek9-mz.124-15.T9.bin

I have a couple of cisco 7920 phones, they are connected to a cisco 1242AG access point which is in turn connected to an NM-16ESW switch in a cisco 2651xm router. The problem is noise and static on both phones and happens with both internal and external (sip trunk) calls. I also have 7940 desk phones on the same router but they do not have any noise problem. What's really weird is if I squeeze the 7920 phone while it's at my ear the static and crackle increases. I tried a different voice codec in the router but it made no difference and I've always used g711ulaw. I also have 'no vad' on the dialpeer. I figured the problem may lay with the access point config but I don't know. Attached is a the access point running config, thanks if anyone can help.

New Member

Re: cisco 7920 ip phone noise static crackle

I found a solution for this which may benefit others....

I took my worst 7920 phone (really bad crackle) and dismantled it.  There are two circular bullseye-type contacts at each end of the phones' circuit board. One connects to the ear speaker, the other to the microphone. I got some isopropyle alchohol and cleaned these contacts thoroughly. I also cleaned the back of the microphone piece (it has three contact dots on it) and the spring contacts for the earpiece. While there I also bent the earpiece contacts up a bit so they'd press harder when re-assembled. I also cleaned the contacts on the battery for good measure. Re-assembled - the phone is like new, sound is perfect, no more crackle.

CreatePlease login to create content