I've googled but it seems I an't find anything about it... Is it possible to connect only to a specified mobile provider using vwdial (or others) ? This is to avoid roaming costs...
edit: nevermind... http://sakis.tel4u.gr/blog/sakis3g/c...akis3g-script/
Force specific ISP code: FORCE_ISP
If your modem does not support AT+COPS commands, which is required for autodetecting your operator, you can still guide this script to use your operator. Assign Numeric ID of your operator to this variable (see list of supported operators).
ATTENTION: This option *should* (is not tested, and it also depends on modem) prevent your modem from roaming. However, if you are out of country, you may be unable to connect.
e.g. to force using GR Cosmote add: