If you are serious about getting into the business, the autoclave is a good investment Loca Glue can be messy and time consuming. In order to leverage your time, you will need the right equipment. The good news: It looks like the price of these machines is coming down recently.
This can happen for many reasons and there are a few things you can try: 1)Go to settings>general> reset > reset network settings. 2) Use compressed air to clean out the SIM port. 3)Try another SIM card. 4) Open up your phone and lift the gold prongs so there is better contact. 5)Clean the gold prongs with rubbing alcohol. 6) Contact your phone carrier, it might be something on their end. This might be also useful: http://vkrepair.com/iphone-6-2/iphone-6-sim-card/