Is it true that roaming cell phones can't work independently of
> resources in the home market?
Yes. They need to check with the home system to see if the roamer has an active account and to exchange billing info.
I would have assumed that the databases they need to refer to make
> outgoing calls (and perhaps the ones for inbound calls to be
> redirected to them in another market) wouldn't be centralized in the
> phone's home market, but be located elsewhere.
Why would they do that? Surely you aren't under the misimpression that disaster survivability drives their network design.
R's,
John