This document explains about the issue faced with AnyConnect Always-on feature on ios and Android phones.
AnyConnect Always-on feature works fine with Windows PC but the same does not work with ios or android supported mobiles. Why this feature does not work in mobile platform?
Always on and TND is not supported on mobile platforms.
Please find below the reasons why Always On feature is not supported in ios and android mobiles:.
1) Always On (enforced) VPN - Including Web Security Appliance tie-ins *
Always On cannot be implemented on iOS because of limitations in the operating system. Also, this functionality might not be at all desirable from a user perspective, as it would have ramifications for battery life and could be chatty as the iPhone moved from wifi to 3G and back under poor signal conditions.
2) Trusted Network Detection
TND is not possible on iOS due to limitations in the operating system. The next-best thing is to use the iOS "VPN on Demand" functionality, which can be used to direct AnyConnect to launch whenever specified hosts are contacted.