Voice Command Contacts no longer working

One of the features that I have enjoyed is the ability to access my contacts via voice command. Recently my phone will no longer allow me to connect to a contact via voice command. I can access the contact using the voice command, the contact appears on the screen of the phone then shortly thereafter it disconnects. Before it would continue and then place the call. what has happened or what can I do to reactivate this feature. I am using and IPhone 7 plus. Thanks,