Do you mean with google voice? Like other respondent suggested, try clearing cache and app data on google voice. this should run you through the setup again. Alternatively, if you have forwarding service from your carrier, check the status of the forwarding to see if it is still set. GV never sets that up automatically for me, I had to go in to the forwarding numbers and change them all to my google num. That seems to stay persistent for me, and works with no issues.