said by bzmeteorite :

CALEA seems to be poorly designed in some respects, for one, there is no publicly published open standard out there that I am aware of, and two, the cost burden is completely on ISPs. That may not matter for the large ISPs, but for the smaller ones I'm sure it does.

said by Mike_27 :

Here's a public standard:
WISPA CALEA Standards (Versions 1 and 2) as produced by the WISPA CALEA Committee and ratified in May 2008.
»www.wispa.org/calea/WCS/

There are also cost effective solutions for small providers:
Netequalizer: »www.netequalizer.com/caleafaq.php
Mikrotik: »wiki.mikrotik.com/wiki/Calea

HTH,
Mike