Why is it that sometimes my calls do not go through?

Many times I make calls and they do not go through - it gets stuck on "Dialing" until it drops the call. Sometimes the go through. the other phone (not BLU) works perfectly with the same GSM in the same area. Same problem when I use 1 SIM card. Same problem when I did a factory reset. Just using 1 SIM since. Also gets constant message: "No SIM card detected". Now thinking of a Flash.