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SPA525G2 - fw 7.5.2a crackling sound



a few days ago I noticed that cisco released a FW update for the SPA525G phones. Until now I used the 7.4.9c FW that comes with the 8.6 UC560 software package. I uploaded the FW to our UC560 edited the load and updated the tftp config. After a reboot the phone just upgraded fine.

Since the upgrade I hear a strange crackling sound in my handset when I'm using the phone. The crackling appears like once every 60 seconds and lasts for 5-10 seconds. It sounds a bit like as if the other party would stutter or there was a "chopping" like effect applied to his/her voice. In Germany with analogue landlines we had some analogue call-charge pulse that sounded quite similiar :-). 

I flashed the newer FW because I thought it might fix some compatibility issues with BT Headsets (I bought a Logitech H800 BT-Headset which pairs just fine with my laptop and iPhone but just won't work with my SPA525G2 using 7.4.9c and 7.5.2a-bt). The cisco SBS support told me that it's not in the compatibility list and they pretty much don't care about it.

So basically I wanted to ask if somebody else noticed the crackling within the 7.5.2a FW and / or has some adice on the Logitech BT issue?




Accepted Solutions


This seems to be an issue only when the Side Car is attached to the SPA525G2 phone. Testing was done using a SPA500DS and SPA500S side car models.

Issues seems to be persisten on all flavors of  7.5.x. Trying to track the issue and get  pernament fix for this.

Regards Yash Joshi CCIE Voice # 31109

View solution in original post


Paul Norman

I am using 7.5.2a firmware on my SPA525G2's i fashed with 7.5.2a-bt and when my iphone 4s is paired with them the audio is utter crap! i had a call only yesterday and it was embarassing lol.

Choppy audio, low audio and im sure it cut's out every few seconds or so.

Did either of you manage to fix this? We're having issues pairing a Bluetooth headset using 7.4.9c software. I noticed there is now 7.5.2a and 7.5.2a-bt (what's the difference?) but if you are now having audio problems then I will not upgrade. I think we are actually going to downgrade to 7.4.6 as apparently Bluetooth is better:

What a load of of s***e?


meanwhile all 4 SPA525G2s in our office were "auto-upgraded" since I deployed the upgrade on the UC560. All phones show the same crackling issue. No difference if internal or external calls.

My solution is to wait for a new release to fix the problem. I don't want to downgrade.

The difference between the normal and the -bt software is often cited as extended or advance bluetooth capabilities. If you don't need BT flash the normal version, because it's faster, since it's about 1 MB smaller. Yeah sounds also strange to me :-)

I don't know the exact differences between the non-bt and -bt versions. I also didn't find anything in the release notes about that. Sorry.



I can help with the "bt" version. The "bt" version has better Bluetooth capabilities and is recommended if you are using Bluetooth features