I use MTN line with my configured 3G phone Sony Ericsson P990i and I connect it to the system via USB or Bluetooth.
MTN has 3 plans that you can use to browse
daily plan or 50 meg with just 500#. Send 103 to 131
Night plan(10pm to 5pm every night) with 3000# airtime send 102 to 131
Monthly plan(24/7) with 10000# airtime. Send 101 to 131. Iam presently using the daily plan with 3G network and it is fast. For more info call me on 08038000194,08053012075 or better still mail me on firstname.lastname@example.org.