International SIM Card
Frequent travelers know that they need a cell phone which can be used with an international SIM card to get the lowest rates in most countries. It's also smart to carry another phone that can be used with local SIM cards in particular countries where you may travel most frequently.
In destinations like England, Germany, Netherlands and Israel this can save you the most money. Examples of phones which work well for this purpose include the Samsung Galaxy SII and the Nexus S. A T-Mobile Bold phone will allow for free calls to the US via WiFi when you use Unlicensed Mobile Access (UMA). This service is offered through RIM and it's only accessible if you have a Blackberry on the T-Mobile network in the US. Rogers and other non-US carriers also offer UMA.