These documents are coming from repository. In my opinion reading only these can help you learn what is needed for a) passing the CCIE Voice written and lab exams, b) get deep knowledge on Cisco Voice technologies (and not only Cisco but voice in general) c) be sure that you are reading actual information that Cisco use to their products.
   This page includes some of the documentation that someone have to read while preparing for the exams (written at first and then for lab, according to the blueprints that is). There is more than these of course but this is the core staff.

   The main page for Cisco's Validated Designs is this Specifically for voice:

  • This document is for 3750 switch which is the switch that you'll find in to the lab:
  • From the Enterprise QoS SRND:  
  • This is a document not so relevant to the CCIE Voice lab exam but in general with network tweaking while using media services. This is video and voice of course but it won't give you anything specific to help you pass the exam. Nice document just for reading though: Medianet QoS Design
You must read everything there except the FXS part.
IOS Commands
  • (soon)
IP Phones

I'm going to add URLs of the documents from web page regularly.