If you have ever tried to get an Unlocked smartphone (like a Nexus 5, etc.) working on Sprint's network, you probably already know it can be a pain in the arse. Our friends at Android Police did a writeup on this predicament and we thought it was worth sharing their very helpful info. Be sure to hit up their full article for all of the details, but here is a snippet below: If you buy an unlocked phone that works on Sprint, but doesn't include the carrier's SIM card out of the box, you're in for a bit of a headache, unfortunately. Sprint SIMs aren't as plentiful and available as they are for other carriers, so you need to do a bit of legwork in order to actually get one. Here are your options to get the phone activated: 1. Find a corporate store, preferably one that does in-house repairs. Sprint-owned shops offering that service almost always have SIM cards since they're treated as repair parts. NOTE: Corporate stores will only give you a SIM if you're activating the device on Sprint's branded service. If you intend to use an MVNO like Ting, chances are very good that they will refuse to give you one. 2. Find a 3rd-party Sprint retailer who may sell you a SIM. I've personally had luck at Best Buy Mobile. They'll generally sell you one for $10. Retailers like this can be hit or miss, though. Call around before you go driving all over town. 3. If you plan to activate on a Sprint MVNO like Ting or Virgin Mobile, your chosen carrier might sell you a SIM but that depends on the service provider. 4. If none of those options are available to you, call Sprint customer service and they should be willing to send you a SIM by mail. Once you've located a place to get your SIM, you have one more hurdle top jump over. Sprint literally has eight different SKUs for its various SIM cards. Each device that the carrier allows on its network is assigned a specific SIM card SKU and the system will only allow activation if you're using a SIM with that exact SKU. This would likely seem absurd to most people (myself included) as, usually, a SIM is a SIM as long as it's the right size. Alas, Sprint apparently doesn't see it that way. If you're getting your SIM from a corporate store, customer service, or an MVNO, this shouldn't matter as they can look up which SIM is needed for your device. However, if you're buying from a 3rd-party retailer, you'll need to have this information beforehand so you don't end up buying the wrong one. Make sure to check the UPC code on the SIM before buying it. Here are a list of all nine unlocked phones currently allowed by Sprint and what SIM you'll need: Nexus 5: Sprint Part #SIMGLW206R SKU - CZ2102LWR UPC - 760492013536 Nexus 5X, 6, 6P, and Moto X Pure Edition (3rd Generation): Sprint Part #SIMGLW446C SKU - CZ2144LWC UPC - 019962040146 Unlocked iPhone 6, 6 Plus, 6S, and 6S Plus (Included For Completeness): Sprint Part #SIMGLW436C SKU - CZ2134LWC UPC - 760492031912 Once you have the right SIM for your device, you should have no problem activating it on Sprint or any MVNO who uses its network. I can't imagine that the carrier will continue to have such a convoluted and confusing policy toward SIM cards into the future, but for now, that's how it is. Hopefully this information will save you time and headaches.