Check your balance. For example, subscribers of Beeline for this you need to dial *102#, and to subscribers of MegaFon or MTS - *100#. On some rates at zero balancing is limited not only the possibility of writing messages, but also receiving them. Fund your account, and expect the SMS will be delivered.
Make sure that you are in range of a network. Possible, close the device, silencing the communication, for example, in office buildings, places of mass events, etc. Sometimes there are temporary technical problems with the network. In this case you can change your location, or wait until the message retry by the subscriber, which will be delivered without error.
Check the properly inserted in the phone SIM card. Required to receive and send SMS settings sewn into it by default, and with weak contact card can fail. Also if you have recently removed and inserted the SIM card in place, can return to the initial state of the message settings. Make sure they are installed correctly and if necessary, change to the right.
Restart your phone. Perhaps the error is in the software and service of sending and receiving SMS messages does not work properly. Restarting the service may help to establish her work.
Contact the customer support service of your operator to clarify the nature of the problem. Call to the short number 0611, if you are a subscriber of Beeline. MTS users can dial 0890, and MegaFon – 0500. Inform the consultant about your problem, and he, in turn, will provide the necessary guidance. Also you can visit the phone store in your town, where professionals will inspect your phone and SIM card and will help to correct the error.