Thanks Tim.
Fair enough, but I still believe the following:

1) I'm not sure I agree that "most customers" take immediate advantage of the control panel. I would bet that many (most?) do not start using the service until they have an ATA, especially if you are trying to market this as a replacement to copper POTS service.

2) Why not simply start billing on the date of the first call, or 10 days after shipment of the ATA, whichever is later? That seems fair to both parties and it would protect you from any debates. It would also allow people who wanted to take immediate advantage of the control panel to do so.

3) At a minimum, you should really disclose this policy up front when signing up for service as well as clarifying it in your T&C's web page. If you did this, there would be no argument.

Cheers,
Larry