I agree, ever since going to 188.8.131.52 (months ago) I have never experienced the call lag again and PRIOR to going to 184.108.40.206 I experienced the call lag ever time I answered the phone. My wife is still running 220.127.116.11, just because i've been lazy and haven't upgraded for her yet, and I can confirm that the call lag has never been a problem on this OS either.
So from my experience
18.104.22.168 = always had the call lag issue
22.214.171.124 = never had the call lag issue
126.96.36.199 = never had the call lage issue
I am with T-Mobile and have been running 188.8.131.52 (like I said) for many months and have no issues whatsoever. So, kevin714, your best be until T-Mobile releases an update beyond 184.108.40.206, you should go grab 220.127.116.11 and you'll be very, very happy with it.
If you are wondering "can I install a Cingular OS on my T-Mobile phone?" the answer is Yes, you can install ANY blackberry 8100 (pearl) OS from any carrier onto any blackberry 8100 (pearl) phone.
You should be able to download 18.104.22.168 from this link (be sure to download desktop manager as well as the latest handheld operating system) https://www.blackberry.com/Downloads...E4F82F9F00E7D4
Else, start at this thread and find your way there, taking note that this thread will help you learn how to install updates to your phone - which in general is a very safe and very well known process. Latest Operating System Available For Each Blackberry Device
Best of luck to you - you'll love your pearl once you get this fixed.. I wanted to throw mine into the toilet when I first got it, simply because of the call lag issue.