In your case , if out of any minimum term , if you renew to get a better deal , then it’s the case that DV will become a part of renewal , you could continue outside of a minimum term , paying more than if you recontracted , but not moved to Digital Voice , but you may get notice tomorrow that you are getting DV , so that’s no guarantee.
As stated already , the majority of migrations are seamless, in my case , I plugged a phone into the SH2 router a few days after the date I was told to move the phone into the router , I even received an email say don’t forget , which I had done , and probably within 10 mins the DV service was working
