Same old song, similar tune, old wish list. Maybe such capability can be designed in to your system as an extra cost feature?

Good discussion about one line, multiple ATAs
http://www.dslreports.com/forum/r205...small-business

The mother-in-law is here for six weeks (she could stay year-round and it would not bother me ) and that makes me long for a second outgoing line that shows my primary number.

This would ideally be offered with a hard cap on shared outbound minutes; Sharing with with primary account outbound.

VOIPo can still boast about the unlimited main single line offering as you already have. Low usage customers may especially desire the extra 2-line convenience.

Make outgoing CID with a choice of main account CID, or second line CID, and you would have a great add-on two-line product offering! Allow call hunt for added popularity. Make us buy a second Grandstream to do this if that helps from a support perspective. (GS supported, soft phone or BYOD unsupported.)