My opinion is that is the smartphone is causing the user related issues then I would not cover it under a contract, if the UC application (that I sold them) is causing a glitch then I would cover that.
I see any labor involved to setup/troubleshoot the smartphone they provide as billable.
They may expect us to be experts on the devices but that isn't hard to do when in my experience most users do not even know how to log into their App stores to get the apps in the first place. Most of the platforms work in a similar mannor so once you have installed and configured one you can do any of them. We have been dealing with this ever since the Blackberry came about and people had no clue how to get e-mail on it. Same concept, different media.
If anyone else has other ideas on this I would love to hear them.