iDEN is what called in Israel "mirs" , here is some info

iDEN Programming info

TErestial Trunked RAdio (TETRA) Tutorial

Good Trunked page

Good Trunking Explain

Another good trunk explain Page

Trunked radio Data Transmitted on the control channel

Trunked Radio Forum

Another Trunked Radio Forum

If you want to monitor the Control Channel Trafic this might help you

Another Good One

Various Trunk detection Softwares

This Software decode MPT1327 Data

Another Trunk Tracking Software