Don't two separate lines have separate contracts? If that were true you could still cancel the older of the two plans regardless of number and still pay a lesser ETF.
yes, but the contracts are accociated with the numbers, so the old number has the lesser etf, but he doesn't want to lose that number. He could just add a line and not close it, but then he's paying an extra $10 month on his plan, and if he already has 5 lines he wouldn't be able to add another line.