First of all, an 8ext is an 8 port expansion module for a Panasonic TD-816/1232 system.  The box it's resting on has either 2 thick cables coming out of it (1232) or modular plugs (an 816), and that's only if you're in the U.S.

Caller ID is delivered by a TD-193 module that plugs into a slot on the motherboard and it delivers 4 lines of CID per module.  

You can plug in any standard single line cordless to the XDP port of your digital set and it will work as the 2xx companion to your set.  There is some programming and codes that need to be dialed to make it work.

Last, Panasonic makes Proprietary cordless phones for the system that require a dedicated extension and have the features of a system phone.  It needs very little programming, only a switch setting on the phone to make it work.  They are a tad pricey, so if you can make a single line set work, it's to your benefit.

LkEErie

no caller id though to slt cordless unless you can find an elusive kx-td 171 card will hand caller id off to one set
 

so who has items to sell me to make caller id work?

I'll have to find out exactly which model it is, it doesn't say anythign on the front panel except for 8EXT

This product is from Canada

do a web search for were to byy an kx-td 193  

Should be a silver sticker on the bottom of the unit which will tell you what model it is. Not sure about Canadian units but USA ones have a circle with a number inside it which tells you which version of software you have and you will need at least version 3 to use a KX-TD171 Card. (Found this one out the hard way and have a 171 sitting in my basement because my cabinet is a -1)

I'd prefer a matching cordless phone to add to the extention.  Any idea which model and if programming is required to add to my system?

parallel ext will NOT pass caller id to a caller id capable
single line cordless phone you will need a kx-t 7880,7885,7895,7896 if you want a fully functional
cordless phone that show caller id and complements the kx-td system.
 

So I guess i'll have to get rid of an extention to add a cordless.

I'm only using 1 phone line anyway though.

Thanks for all the help!