Hi,

here is an other way to configure MNC and MCC stuff :
http://en.wikipedia.org/wiki/Access_Point_Name

In France, we have now FreeMobile wich works in roaming mode with the biggest GSM operator. In order to be sure to use good settings, I captured the full name in APN field.

Example : "free.mnc015.mcc208.gprs" instead of just "free".
Beware : mnc and mcc value in the APN string must be written on 3 characters. That's why my mnc field is mnc015 because mine is 15.