T-Mo has less incentive for it than AT&T because they don't lose as much
with a customer moving on with their phones than -- say -- AT&T would.
But churning is never something carriers are happy about.
It's a bit off topic, but, I 'churned' from AT&T to T-Mobile recently
simply because AT&T refused to allow my kid to have an unlocked Android
phone on the network without forcing me into a mandatory data plan.
What irked me was that AT&T never subsidized the phone! I didn't buy it
from AT&T. They had nothing to do with it - and - my kids plays games but
does not need or want the Internet (except when on WiFi at home).
Point is - AT&T lost me as an otherwise loyal customer, simply because of
their idiotic (I think illegal) policy of requiring a data plan on any
smart phone - even when you don't want or need that data plan!
< / RANT >
The good news is that T-Mobile allows you to have any phone on their
network without a data plan, as long as they didn't subsidize that smart
Even if they subsidize it (as in the ZTE Concord bought at Walmart for
$80), they allow you to put it on the network (switching you from the pay-
as-you-go plan to 2-year contract plan of course), only charging a $30
activation fee and $5/month additional for the SIM card service.
All in all, AT&T is vastly more customer friendly than T-Mobile -
although I find the service coverage almost exactly the same - so the
ONLY difference is in attitude.