Vodafone phones are part of the GSM system, which was designed in Europe for international roaming. So long as you have a dual or tri-band phone, and have arranged for international roaming to be enabled, you can use it in more than 90 countries. The calls are expensive, though.
Telecom phones belong to the US-designed CDMA system. International roaming has to be enabled by Telecom before you can use them overseas. The phones will work in some countries, but not all. Check with Telecom before you leave.