like everyones saying, you can't... you could try, but eventually you'll have to call straight talk reps to activate your phones serial number, which straight talk won't let through unless it's one of their own phones...
Tracfone companies NEVER have allowed other companie's phones on their network. They do this to protect their fiscal ecosystem. Net10 and Tracfone don't allow it and Straight Talk is no exception. The only byod anything that Tracfone companies have is 1)unactivated sims from that company can be used on either Net10 or Tracfone but once activated are going to be locked to one phone and one phone only for the life of the sim.
2)Tracfones can be used to replace Safelink models. The reverse may be true too (Safelink phones on Tracfone accounts).
3)Straight Talk phones have been known be be usable on Page Plus and possibly other Verizon mvnos.
That's pretty much it.
There are other Verizon mvnos that have a no other Verizon phone policies too, Jitterbug and Pure Wireless are two of them. It is up to the individual Verizon mvno to decide its own polices on bring your own device. Some like ST, Jitterbug and PW are zero tolerance but their devices can probably be used on the mvnos that have byod. The ones that do allow byod have clean esn postpaid dumbphones as a universal allowed byod.
All of them but Page Plus also allow all smartphones from VZ.
Others allow Alltel phones and a couple are said to even allow Verizon prepaid phones after six months.
Page Plus though, allows other non Verizon/Alltel carrier phones if they are flashed and not on their banned list (Blackberries, Palms, non meid Htcs).
At least they do for now. Who knows if they will bring in more phone bans in the near future.
Safelink and Tracfone are very closely related. You can upgrade your Safelink phone with a Tracfone model. You can add a Tracfone airtime card (TF cards can be had discounted, SL maybe not). You can add a DMFL card to the Safelink phone to double paid for minutes. If you leave SL your SL phone becomes a Tracfone. If you leave SL before your 365 days or monthly rollovered minutes were used up you don`t loose those remaining days or minutes. Interestingly SL is shipping the LG300G which is not an available TF, only Net10.