Voicemail won't play

I have an iPhone 6s. I can see the transcription of the message but it's not accurate enough for me to understand what's being said. According to the literature, the message is supposed to play while I'm reading the message. The icon changes to indicate that the message is being played but the pointer indicating how much of the message has been played does not move from left to right, the number of remaining seconds doesn't decrease and the message doesn't play.