I'm thinking, even if its not a promotion, general extensions of existing services should be advertised so users can add on as they feel inclined.

Special promotions tag with "SALE!".

Personally, I have a founder's plan, so I never worry about the rate going up or down, or time running out.

Once you try VOIPo, and get accustomed to must-have features, then a little more expensive annual should not be too big a deal.