Also you can use sql ce on the device and use Merge
Replication. You don't necessarily need a web service
reference to invoke a GPRS connection.
For Merge Replication Test with GPRS, you will need:
A SQL Server/Oracle DB.
An installation of SQLCE2.0 on the device. (in Compact
Framework SDK called sumtin like sqlce.ppc.arm...)
Replication on the SQL server DB with publications i.e.
(ORDERS CUSTOMERS GENERIC etc) and merge replication code
using the merge namespace.
After that you can test with GPRS , firewalls etchope it
helps