[Sim800c] How to send AT commands over Bluetooth

Hello everyone,
I've searched too much about the ability to send AT commands to Sim800c over Bluetooth from connected device so we can use the module later without Arduino.

I successfully upgraded firmware of the module to enable Bluetooth features, power on, connected and now sim800c can receive data over Bluetooth (SPP) from the connected device but it just print this data in serial monitor and what I think it can be possible to execute the command and reply to that connected device.

As mentioned in simcom site this module can act as client/server Bluetooth as it can act as client device to send AT command to connected device over SPP. But I couldn't understand the how to around this section at page 63 and next in the below link

https://simcom.ee/documents/SIM800x/SIM800%20Series_Bluetooth_Application%20Note_V1.07.pdf

For example if we want to use sim800c as client and send AT commands to server we can use AT+BTATD=+1234567; and the connected device will dial up this number as same as ATD+1234567;

But how to send AT commands from the connected device to Sim800c over SPP witch already supported Bluetooth profile in Sim800c, I think in this situation sim800c will be server and the connected device will be client.

Is that not possible?