Straight Talk to Allow Any GSM Phone on the $45 Unlimited Plan
Previously, you had to buy a Nokia smartphone, do a sim swap, keep the Nokia, and not tell Straight Talk. Now, you do not need to do that anymore. Plus, the Nokia only worked on AT&T towers. Looks like Straight Talk will have a sim for AT&T and one for T-Mobile. What sim they give you is probably based on the coverage in your area.
Updated: Now that it is passed Feb 7, we know that you select the sim: an At&t, T-Mobile, or Unlocked. Blackberry, or branded TracFone, SafeLink, NET10 or Straight Talk phones are not supported. Hence, your At&t or T-Mobile phone does not have to be unlocked.
When people did the sim swap previously, they tried to stay within 100mb per day and 2gb for the month. Some people have said that they have used more than that amount without issue. Whether this amount changes because there will now officially have more data intensive phones on the network remains to be seen. None of the mvno's are truly unlimited anyway and put such terms in their agreement because they do not want abusers.
Straight Talk and Net10 are owned by América Móvil. Straight Talk is for Walmart. Net10 is for other retailers. Do you get anything more by paying $5 more to Net10 for their $50 unlimited plan? Most likely not. Walmart itself does not sell the sim. You must purchase this online.
As far a roaming goes, there was limited roaming using the sim swap. I expect this to be the same but will wait for reports.
If you have an At&t phone and get a sim, then it seems like it is the same speed as the sim swap. Not sure what happens with a T-Mobile sim yet, because most T-Mobile phones do not support 850 and 1900 bands in 3g.
Note that the sim only works with the $45 Unlimited Plan. You cannot use the sim + your own gsm phone on any of Straight Talk's other plans. For the other plans, you need to purchase a Straight Talk phone.
Looks like T-Mobile phones will get 3g with this plan after all. It might be that the 850 and 1900 reference is directed at unlocked phones owners as Straight Talk might be sending those people the sim for At&t phones.