Edesy does not assign internal extensions or support 3-4 digit internal dialing. What you can do: route callers to people and teams with an IVR keypad menu and forwarding rules, or keep the PBX that runs your extensions and connect it to Edesy numbers over a SIP trunk.
Numbers from Rs 449/mo
No Hardware
Rs 20 Welcome Credit
Keypad menu per team
Forwarding rule per team
SIP trunk for your PBX
FreePBX 17 setup guide
New accounts get a Rs 20 welcome credit; no card needed to sign up. Prices exclude 18% GST.