[VOIPSEC] Cisco call manager encrypting signaling and voice

[Juan B]

Hi all

i am doing a voip security consulting for a big client of mine.

I want to recomend to implement call encryption. the client has 6 cisco call manager version 6.1.3.1000-16 it is an appliance. according to a menual im reading call encryption can be done only if call manager is installed on windows 2000/2003 is it true?? i foud a menual named secoview.pdf in the internet.

can someone also please send me a good hardgning menual for all the Voip installation ? the client also has as asterisk version Asterisk 1.4.20-1 (toxbox) in the dmz. 

thanks a lot for your help.

juan