How to create a test to measure end to end audio delay
I recently ecountered this problem too (about a month ago). This is what I found..

Network delay measuring protocol (NDMP) - little useful free-ware program. I used the same program to measure other VoIP call delay.

You can download it from here: http://www.unforgettable.dk/42.zip
ReadMe file is included in .zip file.