*123# | *1345# [dial]
Request Own Number
IMEI Serial Number
Request to Recharge Balance
Show Status of Call Waiting
Display phone software [Samsung and Nokia]
Request Account Balance
Call Forwarding Status
*355# | *335# [dial]
Request for Data Bundle Services
Show Status Call Lock
Prefix for All Calls Operated in Zambia
Every mobile device is coded with special numerical characteristics to identify and make it usable for a number of services as designed by the manufacturer. Together with the Mobile network provider-services the special codes form to work well for the customer. Its such provisioned and enabled services that allow a user to check credit balance let alone request for credit adjustment.
Let’s say you have a cell phone, you turn it on and someone tries to call you.
Here’s what happens to the call:
- When you first power up the phone, it listens for an SID on the control channel. The control channel is a special frequency that the phone and base station use to talk to one another about things like call set-up and channel changing. If the phone cannot find any control channels to listen to, it knows it is out of range and displays a “no service” message.
- When it receives the SID, the phone compares it to the SID programmed into the phone. If the SIDs match, the phone knows that the cell it is communicating with is part of its home system.
|A Telephone Tower|
- Along with the SID, the phone also transmits a registration request, and the MTSO [Mobile Telephone Switching Office] keeps track of the phone’s location in a database — this way, the MTSO knows which cell you are in when it wants to ring your phone.
- The MTSO gets the call, and tries to find you. It looks in its database to see which cell you are in.
- The MTSO picks a frequency pair that your phone will use in that cell to take the call.
- The MTSO communicates with your phone over the control channel to tell it which frequencies to use, and once your phone and the tower switch on those frequencies, the call is connected. Now, you are talking by two-way radio to a friend. Read more here
Codes for Samsung phones
Display software version
Display firmware version
Display hardware version
Reset: delete all data and reset all settings
Test/service mode, e.g. Galaxy S3 mini
Test/service mode, e.g. Galaxy S2