In the process of moving to Ting, and have a few comments that might be worth sharing.
I bought refurbished Sprint phones to move over( 2 HTC EVO 4G). The porting activation process does take a while, they say up to 24 hours and they mean it. I'm not sure if that is typical but ported three phones over in the past 5 days, and that seems to be the case for each one. For some reason I was expecting that magic to happen sooner, like an hour, when they say up to 24 hours, they really mean it.
Customer support is only available between 8am 8pm easter Monday through Friday so if you need to port over a sprint phone, you should time it so that Customer service would be available when you are ready to switch.
If you are porting a cell number that takes like an hour or three (from T-mobile), if you are porting a land-line that will take a week. If you are porting over a number from google voice, that is like a land line and will take a week as well.
I entered an incorrect ID number for one of the phones, and took a while to figure that out, totally my fault, but the customer service was incredibly helpful. (I am not counting that error on my part on the activation time for the phone)
I have to say the customer service with these guys is wonderful. Compared to every other helpline I have ever dealt with they are pleasant, intelligent and truly helpful. However one minor minor point. Because they are so competent they assumed (falsely) that I was able to accurately read and enter the ID number for my phone. If they had verified that with me sooner, they would have caught my error a little sooner. It is really hard to complain about an error I made, so if you are moving over a phone, take the time to verify and double-check all the information you enter and provide.
Overall the process of bringing over a BYOSD was still a little clumsy. I think this is technically still a beta for them though. I hope they will tweak this a bit and things can go more smoothly in the future. The amount I will save on my bill is staggering though so well worth the hassle.