I'm with cingular and when I'm at work I roam on t-mobile, "cingular extend". WhenI first got the treo 600 I had a full strength GPRS signal and used it a couple of times, now I still have 4-5 bars but no GPRS symbol. I wonder if cingular cut out GPRS roaming, because I've heard of people not getting charged for data while roaming.