Making the switch from Boost mobile

DaemonKane wrote:

Is there any promotions/discounts for new cell phones through T-Mobile, like boost Mobile did for Virgin Mobile customers when making the switch?

Also I have a custom plan for being a loyal customer for around 15 years starting back with Virgin Mobile ( I would get special discounts for never letting my account default ). My question is, since I've been a loyal customer with Virgin Mobile into boost Mobile for a decade and a half plus, am I able to keep my current plan with T-Mobile if I make the switch? 

Even if Tmobile let you keep your plan when you switched once you buy a new phone from them on a promo you would need to switch to a Magenta plan.