Does the DK40I have caller id capabilities and if so what is needed...add on, new processor?

Adding a TCIU piggy back card onto the TCOU in the base cabinet will provide 4 caller ID circuits. Another way is to install a RCIU or RCIU/RCIS in an available expansion cabinet card slot.

Thank you.

You could go ISDN with the TBSU or RBSU in an expansion slot this will give you CLI on incoming calls.

I looked for one of these cards for a customer. I ended up recommending just upgrading to a CIX 40. Those TCIU cards were pretty pricey when I looked last time.