Are refurbished phones locked with a carrier?

Refurbished phones can be locked with a certain carrier. When buying a refurbished phone, be careful with its specifications. 

How to filter refurbished iPhones by carrier or unlocked

At RefurbMe, we offer a few Carrier filtering options. When you search for an iPhone, click on More Filters:

Scroll down to Carrier and select the option(s) you want:

As you can see, one of these options is "Unlocked". Unlocked phones are compatible with any carrier. This can be a good option if your carrier isn't listed among the list above. You can also unlock your iPhone if certain conditions are met.