OK for many of the four line and above PBXs the phone will not work with the FXS port.
Easy way to test is take and plug the phone into a STANDARD TWO wire jack (like a fax machine or home phone)
those 4 / 6 / 8 line phones will not work without an adapter which is VERY costly (24 ports over 3000.00)…and in many case you end up with a phone which sounds like a 40.00 BT phone anyhow…
So at 125.00 plus a port to convert it may be wise to look at IP Phones
for the nortel / panasonic KX folks who wish to CHEAPLY add VoIP lines to the system, we just hang a ATA off it and have the users use the VOIP line to call out when needed…
Add a few paths (pipes) to the main Analog lines and add CWoNA / CWoB to a VoIP DID setup on the ASTERISK and all is good…
In my office witha Nortel KSU
If I hit line 1 or 2 I go out over the PSTN via the Nortel KSU
If I hit line 3 or 4 I go out over a VoicePulse line (ATA’s hanging off the KSU Co ports) setup as exten on remote box passing the CID of the PSTN lines)
If I hit line 5 or 6 which are ATA’s setup on two remoted hosted PBX’s
I am hitting other PBX’s as an exten and can call internal as well as outbound from the remote boxes as exten on the remote systems and I Pass the remote boxes CID’s.
We all use the Nortel Phones and softphones w/ USB headsets on the PC / Laptops
The way it is setup we all can look at the phones and see which line is ringing and know how to answer the phones.
The three groups are answer different
1-2 company one (pots with CwoB / CWoNA to VoIP 4 VM / follow me)
3-4 company two (CVP Voip lines)
5 company three office A (Exten on remote box a)
6 company three office B (Exten on remote box b)
No local asterisk box all boxes are remote, which is why no FXO card in a Asterisk server.