call audio

[qiset]

The call audio is too bad to understand.  Broken mechanical static.  It is bad
for both incoming and outgoing calls.  I've tried the sound settings for the phone 
but nothing makes a difference.  Any clues?

An update.  I connected to wifi and was able to hear youtube with no distortion.  
I tried a sim card from a cricket phone.  Later I tried a sim card from a freedom pop
phone.  The one from the freedom pop phone was recognized but it didn't work at all.  
Could it be that the card needs to be authorized to the phone in some fashion?