What is a USSD code, and why does it differ by operator?

USSD — unstructured supplementary service data — is a facility of the mobile network that lets your handset send a request straight into the operator’s system and get an answer back immediately. Its great advantage is that it needs neither internet nor a smartphone.

The reason they differ is simple: the codes are not a universal rule of the network but each operator’s own addressing. The balance code on Teletalk is one thing and on another network something else, because each operator has arranged its own menus. The same operator can also change a code over time.

There are exceptions, though, and they are useful to know. Dialling *#06# shows any handset’s IMEI — that is the phone’s own code rather than an operator’s, so it works on every network. Likewise *16001# is the national SIM-registration check and works from any operator’s number.

Two practical rules. First, take your own operator’s codes from its own website or app — a code on a third-party blog may be out of date. Second, never dial a code someone reads out to you over the phone; some codes switch on call forwarding, and then your calls and messages go to someone else’s number.

Sources:

• Teletalk — frequently asked questions