Background. I have two lines on a "regular" account. (Think TM calls this new account "Simple Choice") My brother, who is 11 years younger and in the dark ages, cell wise, just has a TM prepaid phone. (I gave him an old dumb phone to use a few years ago.)
The experience did not start off positively. Turned out I asked for the wrong dept. and for the first time ever, got an overseas CS person combines with a poor connection. I was told my brother had to go to a TM store and get a new SIM. It turned out that no notations were made on my account.
Brother goes into TM corporate store and was told I had to call in to TM to authorize the addition of another line. (I had thought this was done. This time I told the computer voice "add a line" instead of saying something more generic. Within a minute got a holpful CS lady who said "no problem". She quickly verified it was really I on the phone, said she would conference in my brother who was still at the TM store. When brother had first gone to the store, he was told they would have to give him a temp number. The CS lady on the phone said she could simply mail him the proper SIM AND waive all set up and other charges. He would get his new SIM in the mail in 3-4 days and she gave him a number to call to activate it when he got it. After she got his address, he hung up, kept me on the phone while she read thru all the fine print she was required to read plugging in "zero" any time the form required an amount to be entered.
What I can't figure out is, how TM will make money on this. The 3rd line adds only $10 to my bill. They have no way of knowing we will almost certainly be with them for years. (I have been with them since they were Omnipoint 17+ years ago.)
Moral of the story. Do a family member a favor. Have them get on your account. Lines 3,4 and 5 are only $10/mo. if they only use minimal data. Unlimited voice/text. I only use data for email and that never exceeds the 500MB minimum. (Wife does use Pandora a lot and hits 1G or so, and extra $10/mo.)