We took a very, very, hard line on this as $2500 roaming bills were common place and some individuals had a pretty dismissive attitude about it. I found a few of these individuals antagonizing because I knew they were already traveling with a personal phone setup with a local SIM.

Ultimately we just didn't give them a choice in the matter, telecom costs (not just cellular and roaming) were out of control and we got direction from the very top to reign them in. But made it as simple as possible. The phone would be pre-programmed with all their contacts prepended for seamless international dialing and we would setup a local VOIP DID that would call forward to the international number and if they wished they could forward their cell phone to that local number as well.

As a bit of a carrot we made all the loaner devices new iPhones. Practically speaking the only real problem we encountered was some carriers brutally throttled prepaid data and not roaming data.

We probably could have setup a side-business selling SIM cards because they began turning up with their kids, friends and spouses looking for the same setup for their personal use.