To check the PNR status of a ticket, type PNR followed by your 10 digit PNR number, like this,
PNR1234567890
and send the SMS to 139.
This service is available for all mobile service providers except BSNL and Reliance.
Other...
more... than checking the PNR status of a ticket, you can also call to this number to get all the information related to a specific train. Also, the call made to this number (139) is treated as a local call throughout the country