SendCommand Method
Will format and send a PDU using the specified command identifier and payload.
Syntax
async smpp.sendCommand(commandId : number, payload : Uint8Array): Promise<Uint8Array>
Remarks
This method offers a way to do more with the class than is directly supported. This method takes a command identifier and a payload, which includes every required and optional field after the header, and will create the 16-byte header for it before sending it to the server. The response PDU is returned both in the PITrail and by this method.