Cingular data can't get to Bellsouth DSL?

I got a nokia E62 and set up various email accounts without issue. The
phone has an "email settings" data connection profile, which uses the
usual WAP settings and bypasses the proxy servers. Connections to
various email and data services (pop3, pop3s, ssh) work fine, except to
a system hosted on a Bellsouth small business DSL connection in
70.144.0.0/12.

Normal WAP connections come from IPs in the range of 66.209.0.0, which
map back to Cingular data service. Non-proxied connections come from
IPs in 166.128.0.0/9, which is registered as a CDPD data network.

There is no reverse DNS on this CDPD network, but I have no indication
that _any_ data is getting through to the Bellsouth ADSL network.

Has anybody else had trouble getting to Bellsouth DSL-hosted services
from a Cingular data device? WAP/HTTP is OK, but nothing else is. I've
seen the 166.128.0.0/9 network listed in various ISP blacklists
(apparently it's shared with other mobile data providers).

Bellsouth and Cingular don't send a very good message if they're
blocking each other... they're supposed to be a happy family.

tg.