[MENTION=63376]shaheerk[/MENTION]
This could explain the garbage call quality on Jazz, especially during off-net calls.
I called a Telenor number, and then later a Ufone number as well. I could hear and understand the other person, but the voice was muffled.
Decided to open ServiceMode while the call was running to see if it was on 2G or 3G, and unsurprisingly it was on 2G, but I noticed it said AMR_NB instead of AMR_WB.
Now, just to test, I called my other Jazz number and it stayed on 3G (2100 MHz) and said AMR_WB, but when you call another network, it switches to 2G (900 MHz) and uses the AMR_NB codec.
Check the screenshot below.