Ok, so this sounds like a configuration error with your Google Voice account. I don't understand how you are also using voip.ms. Do you have an inbound phone number from voip.ms? If so, does it work? Let's look at your Google Voice settings.
Please log into your Google Voice account from a laptop or desktop computer, not from a mobile phone or tablet, and then take a screenshot of this entire page:
https://www.google.com/voice/redirection/voice#phonesIf you need help learning how to take a screenshot, see these instructions:
http://www.take-a-screenshot.org/Obscure (cover up/black out) the first six digits of all phone numbers, leaving the last four digits exposed. Obscure any email addresses, too. You can use any basic image or photo editing program, such as MS Paint, to cover up the private fields.
Click the "+ Additional Options..." link to attach the image.
Thanks.