Porting from Vonage to Xfinity Voice

I signed up for Voice last Monday, and talked to customer service to start the porting of my phone number from Vonage to Xfinity.

I just checked my account this morning, and it’s now showing that Xfinity Voice has been activated, and with my old phone number as requested. But voicemails are still going to my Vonage account.

How can my phone number be “active” on two services at once? How can this be rectified so I can cancel my Vonage account?