I'm glad that you asked! It will be my pleasure to look into the merge calls option for you. May I ask are you initiating the calls to two people? If so then the option to merge will be on the screen. If you can provide us with the details then we can proceed.
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I'm already on a call but someone else calls in the middle of the call. In the past I was able to place the first call on hold and answer the incoming call and the merge the two calls. Now the merge call option is grayed out.
if you have VoLTE turned on you can merge them the same way you did on AT&T.. so make sure you have HD voice on your Verizon account selected, and LTE for voice and data checked in your phone settings.. This will only work on LTE however so if your phone is on 3G it wont let you merge an incoming call.