You are going to find that there are a lot of error messages that can occur with your iPhone, either during the syncing process or on the device itself. Most of these are either meaningless for your everyday use or are relatively easy to fix, and will not interfere with your work in the same way that error messages on an actual computer may. Since the iPhone began employing SIM cards as a way of transferring over Contacts from older phones there is a new message that has shown up, “No SIM Install.” Here is a look at how to deal with this specific SIM alert.
First, this message is going to be specific to GSM iPhone models only, and not the rest of those available. GSM is specific to the AT&T and T-Mobile networks, which essentially means that this only applies to iPhone’s on the AT&T network. Sprint and Verizon phones are on the CDMA network.
When this issue comes up you can start by removing the SIM card and taking a look at it. See if damage has come to it or if it is dramatically dirty, and if it does have issues you can choose to either replace or clean it. Once the SIM card has been determined to be in correct working order, at least by appearance, you can put it back into the iPhone and then do a hard restart on the iPhone. This means turning the iPhone all the way off, waiting for a few moments, and then turning it back on. After two to three minutes you can then go into the iPhone and see if the SIM card has now been registered. In general this simply requires that you give the SIM card area a jolt by removing it, putting it back, and restarting the phone. If it continues with the same error message then the SIM card is likely to be damaged and may need to be replaced. It is at this point that you should contact Apple support and possibly take it into a Genius Bar.
You can also try a second option where you remove the SIM card and place it in a second phone, which should be an iPhone. If it works just fine then you may have an issue with the connection between the SIM card and the iPhone, which will mean that it does need servicing. You could then use the SIM card in another phone while you wait for your damaged iPhone to be serviced.