In case you have not received a USSD notification after a call / sending of an SMS massage, you can check your balance on your own by means of USSD request *120 # and a call key.
The reasons of non-delivery of a USSD notification:
- no network coverage;
- subscriber is unavailable or the phone is switched off;
- signal path is busy (the subscriber is making a call, has established a internet-session, sending MMS etc.);
- network does not support USSD (in case of roaming);
- phone does not support receiving of USSD notifications;
- phone problem (it is characteristic for Siemens models)
This information can be specified in the user manual to the phone:
1) phones with support of USSD phase 1 do not receive notifications from the operator, and the USSD menu use can be limited to one session (i.e. 1 request – 1 answer);
2) phones with support of USSD phase 2 + can both send USSD requests, and receive notifications.
In case USSD notifications are not received because of a problem in the phone or the phone does not support receiving of USSD notifications it is possible to recommend either to change the phone or to control the balance by means of the USSD request *120# and a call key after each call on ones own.