Simcard not recognized iPhone 3GS iOS 6.1.6 I've updated my jailbroken iPhone 3GS via iTunes restore to iOS 6.1.6, but after the update I am not able to activate my iPhone and its showing no service. 

It says no sim card is installed in the device which you are activating, although it is inserted.  

My iPhone is stuck on the activation page and I cannot use the iPhone because activation is required.
Remove the Simcard and place it back, get a paperclip to do this for an iPhone 3GS.

Try it (several times if it does not recognize it after one try) and it should recognize the simcard.