Exchange authentication with certificate on iPhone

Hello guys, I need help for a configuration on LTM. We have a VIP for the Exchange service, that works fine with all clients. The customer also want to configure client authentication via certificate, installed on iPhone devices, with username and blank password. Which step we must follow for configure this service? We must configure the "Client Certificate" to request (only some devices has the certificate); which certificate i must put on the "Trusted Certificate Authorities" options? I need to import the certificate that client use on my F5? Other question..if i made a tcpdump with the client IP address, i don't see any packet on my VIP. Any suggestion? Thanky ou very much. Best regards