Problem:- Can't send SMS, text messages. SMS centre (SMS Center) number disappears / won't store in ZTE 158 when handset is power cycled. Web search shows problem exists for other manufacturers' handsets as well.

Solution:- SIMM Version is incompatible. Upgrade SIMM to later version.

SIMM version is printed under the Gold contacts on the SIMM.

1204 BIP - Bad

1204 .0002 - Good