I think I've figured this out and wanted to share so that others know what's going on. I had 2 phones, one for my wife and one for myself. Both phones are using one apple id; I did this so I wouldn't have to purchase the same apps for my wife's iPhone. With both phones set to the same apple id, the iMessages features do not work - specifically audio 'texting'. I found that when I placed my wife's phone under her own apple id, the audio text features worked. So if you are wanting to text to another device with the same apple id, you'll likely have problems with this feature.