Voice quality deteriorates

[Tango41]

Periodically, voice quality on my Droid X2 and my wife's Droid Global-2 begins to deteriorate. It seems to happen about every two or three months, requiring that I update something.  I've gone to Settings -About Phone - System Updates, but found I have the most current operating system.  So that isn't it. 

In the past, I've been able to update my phone by calling in to a number and entering an option #2 or #3, as I recall. Unfortunately, I failed to store the number, so I can't do it now.  Does anyone know the number? 

[tikibar1]

*228, option 2 (but don't do this if you get a 4G LTE phone; updates are handled by the SIM card)