I was making plans to see a movie for a friend's birthday and I wanted to talk to both friends who were going to come. I was already on with "Friend 1, so I added the call to "Friend 2". Once I was connected with "Friend 2", I tapped the merge calls button. For one second it said, on the top "Friend 1 and Friend 2" or "Conference" then it just switched back to just "Friend 2". Later, I was on with "Friend 2" and I wanted to call "Friend 1" and merge the calls again. This time it worked fine. If it matters, "Friend 1" has Verizon and "Friend 2" has Sprint. Has anybody else been having problems like this? How did you solve it?