When purchasing a cell phone or phone plan, you are normally asked for a Social Security Number (SSN). If you do not have one and are not eligible for one, you may be asked to pay a security deposit, which can vary according according to the provider. There are alternatives to avoid the SSN or deposit requirement: One is to buy a prepaid mobile phone, which is possible to do at local stores such as T-Mobile in Harvard Square; Another is to use Cellular LD to make international long distance phone calls from your mobile phone.
Mint Mobile offers prepaid wireless cell phone plans and operates completely online. After getting a prepaid sim card (request one from the OIE), you must download an app through which you can choose your plan. They have 3 month introductory plans with the option to renew if you like the service.