I have been using my new Samsung Galaxy S5 for a few weeks now without incident. But recently I discovered that I can't successfully send a text message to a few of my contacts. When I try to send a text I immediately get a message saying that it failed to send. I am using Textra but I have tried using Samsung messages and Go SMS Pro but there is no difference, they all fail to send the messages. I've restarted my phone and tried a number of different things to remedy the situation but nothing has worked. I need to text some of these people for work so this is a big inconvenience, please help!