With money 
Sometimes it gives me an error message...
If your dialing everything correct. And the account has funds.
The only thing I can think of is your not connected to a good network.
Are using a public wi-fi? Or are you using your mobile data?
That plays a role in Google voice like I've once wrote about when using Google voice abroad, and the same would apply here if you're using Google voice and you're not connected to a good Network.