Not everyone has a legitimately unlocked iPhone 4 and not all of these users with an unlocked iPhone 4 switch between 2 SIM cards. And if you are among that tiny group of people who have used more than one SIM on your unlocked iPhone 4, you may be facing this issue.
It is being reported that such users see a message that reads “Waiting for Activation” everytime they access the FaceTime video calling feature using the second SIM. Now it is not clear if all the user in this group face the issue though it is clear that this is not an isolated problem.
Apple has not acknowledged the issue and so there are no official resolution procedures. But if you are facing this trouble, check out the following resolution procedure. For whatever it’s worth, a member at the Apple support forum writes,
“The only thing I did different was having read some posts elsewhere, was activate Facetime on the phone when on a wifi connection and then navigate to Settings > General > About > and leave that page open for a minute or so, then go back to phone and the waiting for activation page was no my number will be shared with other Facetime users.”