The SIM800 series GSM modules from SIMCOM supports Bluetooth functionality. In order to avail this functionality you might need to update the firmware of the GSM modem you have. This blog post is intended to show you how to enable the Bluetooth functionality in SIM800 modem.
To test whether your GSM modem firmware supports Bluetooth give the AT command
If the firmware does not support Bluetooth then you will get an error message. Otherwise, you will get a reply as follows
<status> varies from 0 to 36 depending upon the present state of the Bluetooth Module.
You can download the firmware that supports Bluetooth function from here.
For details about updating the firmware of SIM800 modems visit this post.
After updating the firmware check with the above AT commands. You should see the correct reply.