I was asked to redact a post I made on using third-party SIMs in a world phone. The original poster had an HTC Droid Incredible 2 World Phone on Verizon, was traveling to Singapore, and had some questions on how to make it happen. The following information has some Verizon-specific details, but by nature of the SIM standard, the general concepts presented should apply to any phone that has a SIM (or microSIM) slot. ... when you bought your phone, it came with a Verizon-branded Vodafone SIM installed in the SIM slot (underneath the battery). When you are out of Verizon's CDMA coverage, such as is the case when you leave the United States, and your phone gets switched (more on this in a sec) to Global Mode, that basically means "use the SIM card for voice and data". The phone comes locked to the Vodafone SIM, and as long as you want to use that SIM, you do not need to get a SIM unlock code from Verizon. You do, however, need to call Verizon International Services to enable the Vodafone SIM. You can call collect, 24/7, to +1 (908) 559-4899.The advantage of using the preinstalled Vodafone SIM is that you keep your US phone number, and any costs you incur "conveniently" appear on your Verizon bill. The disadvantage is that it's ridiculously expensive data & voice rates. I use about 350 megs of data per day working as a remote software developer, so that would cost me $1,750 per day for data alone. It will cost you $2.89 per minute to make calls from Singapore, and something like $5 per megabyte of data usage. See here. Verizon hopes you don't realize you have alternatives, but you do.If you would like to use an alternative non-Verizon/Vodafone SIM, you can. You need to call Verizon International Services, get and apply the SIM Unlock Code to your phone (I suggest you keep them on the line and walk you through it, it is non-intuitive), and then buy a SIM from a local cellular service provider where you are staying. See here. Caveat: You must be a Verizon customer in good standing for a minimum of 6 months before the will give you the SIM unlock code.To use the SIM card (either the built-in one, or one you acquire & install), you need to switch it to GSM mode, and optionally tweak your cellular data settings: Menu : Settings : Call : Preferred Network, set it to "Global Mode" Menu : Settings : Wireless & Networks : Mobile Network If you want to use the cellular data service, you want to enable this checkbox, and then go into Mobile Networks : GSM/UTMS Options, and set up your APN and your network operator. If you do NOT want to use cellular data service, keep this off Here is a pleasant surprise to all of this. If you are exclusively using the cellular service of a third-party SIM card (such as you would be living in Singapore for 3 months and using a Singaporean SIM), then there's really no point keeping your Verizon voice/data plan active at the same time, since it's not possible for you to use it. Verizon lets you freeze your plan so that you don't have to pay for your service, with one caveat: the interval during which your plan is frozen doesn't count toward your once-a-year-upgrade deal; it pushes that date out respectively. I had to speak to a few reps and get transferred to International Services before I was able to freeze my plan in this fashion, but once I got someone who know what they were talking about, it sounded like they do it quite often. That's it -- it should work. Good luck.