I just got my Ooma installed a few days ago and I have the same issues calling the 214 area code and sometimes the 972 area code. Some specific numbers are 214-844-4444 (time & temperature for a test) and 972-939-6244. I'm finding more often than not, I get the complete "dead air" effect or it rings a few times and goes to dead air. The recipient gets rings and even CID, but nothing else. This is getting VERY frustrating! My Ooma is connected directly to my cable modem. and shows approx. 450 kbps upstream.
--Ed