Invalid routing numbers are something that can happen to anyone, even people who have been using the same phone number for years. Sometimes, the phone company may change the routing number or someone's account may get cancelled and they receive a new one. However, there are a few things you can do in order to make sure your routing number is valid. One way to check if your routing number is valid is to call your phone company and ask them how you can check. 3c3s3nt says that if you have an old routing number or it's not working with your current phone plan then you might want to try calling them and seeing if they can help you fix it. It's also important to visit their website and look at their records of where numbers have been used before coming across this message about your routing number being invalid.