How to connect a system IP telephone to a PBX?

Question

Telephony

Hello. Actually, I can't think of anything. We have our own PBX and there are telephony providers who provide us with numbers. Authorization we have on a pair of login-password. And there is 1 system IP phone. So I can’t figure out how to authorize an ip-phone so that it works on incoming and outgoing calls, and also works on internal numbers like other phones? You don’t have to speak in detail, but simply write the algorithm of my actions, I’ll get there myself. Thank you.
UPDATE: Panasonic KX-NT343 phone, Panasonic TDA200 PBX

Answer 1

system ip phone can work only with automatic telephone exchange. it means that the provider must register it. you need to make a SIP trunk on the PBX and route calls from it to the ip phone. set up an output from the ip phone through this trunk.

Answer 2

Not "system", but with additional programmable buttons (possibly with BLF backlight) or several panels with those.
They are configured as well as ordinary "mortals".
There are separate settings for the buttons.
It strongly depends on the model of the device.