I assume you have gotten the sim card from the provider. In that case it is likely the reader (the phone). If you have an old phone laying around (or someone else with the same carrier) you can test the sim card's functionality. If it works in another person's phone then it must be your phone. I recently had a similar problem with my Samsung S3. What I did was I put a small piece of paper behind the sim card. This pushed it up against the contacts and is working well as a temporary solution. If this doesn't work I suggest looking to see if your phone can use a different sim card size. Mine has a micro and a standard sim, you might be able to get a different size sim card if it is just the reader portion of your phone.If these solutions fail then it seems you will likely need a new phone. I hope that isn't the case. I hope this works for you!