Thanks. Stupid me believed "...the company is now offering..." when I read it above.
I clicked on the link to get the real details. Then the fine print. Appears this is a temporary promotion for users that currently have the 1GB plan on 4 lines, because that's what this will revert to when it's over. Hopefully our 5 line 1GB plan will have the same benefit come July 30.
The deal is for 5 lines as well. Chatted with a Tmo CSR and they changed my account to now have 2.5GB/line through 1/2/16 starting on my next billing cycle. Took no more than 5 minutes. I'm still astounded by the competence and pleasantry of Tmo CSRs.