is possible to like send commanders through the application like example calling the numbers using say the application developed
That would be device-dependent. You would need to find a manufacturer and model that supported some type of USB or Bluetooth interface, or possibly an HTTP interface if it was its own webserver (similar to how an ethernet router or webcam works).
These are surprisingly hard to find
but if you don't find anything with an interface that your app can connect to, then a Plan B solution might be to note that many of them use 433.92 MHz radios, and so if you acquired these:
https://www.espruino.com/433Mhz
and hooked them up to an Arduino-ish board that you can communicate with from your restaurant(?) app via Wifi, then that might get the job done.
(plus it'd be doing double-duty as a software-protection/licencing dongle for your app too - bonus!)
You'd look at the data out line of the receiver when calling a pager, and then later emit that same bitpattern via the transmitter. Akin to a tv/vcr/dvd learning infrared remote control.
The author of the above page seems to have done this, but for controlling wireless power-point switches:
https://www.espruino.com/Remote+Control+Sockets