In T-Mobile US's case, pre-paid services like the pay-as-you-go or Monthly4G plans do not have access to the full set of towers that the contracted plans do. Per a sales rep I talked to yesterday, the non-contracted plans exclude domestic "partner carriers". This comes up if T-Mobile is poor in an area and they contract with AT&T for coverage.
Yeah, but it's not really that much of a problem compared to dealing with goddamn Verizon. $50/month for unlimited everything is pretty decent.
Admittedly, the instant I move from Massachusetts to Haifa this September I'll be heading off to a mall to find a new phone plan. The entire bleeding country over there basically runs on no-contract SIM plans, so the competition has dragged prices way down. Their equivalent of my current T-Mobile plan costs about $22/month (including VAT, as far as I know) and includes unlimited international calling (to either North America alone or North America+Europe et al depending on when you want your data throttled).
