Causes of this problem range from some simple configuration errors to an unrecorded phone move.
To resolve this issue, check for these situations:
Is the Automatic Location Information (ALI) data for the emergency response location (ERL) correct? Refer to the Creating ERLs section of Configuring Cisco Emergency Responder
Is the correct ERL assigned to the switch port to which the phone is connected? If not, there could be two problems:
Did the call come from the default ERL (assuming you do not use the default ERL for any permanent ERL)? This could indicate these problems:
For more details about troubleshooting Cisco Emergency Responder, refer to these documents:
I need to remove the ERL from the port configuration.