Want to get the Nextel i580s to work with the T-Mobile sim cards. Will it work?

I have two Nextel i580s that use sim cards, will my T-Mobile sim cards work with the Nextel phones EVEN if I try to get them unlocked?

Want to get the Nextel i580s to work with the T-Mobile sim cards. Will it work?
No. Nextel's phones and network are iDEN. T-Mobile's phones and network are GSM. While both use sim cards, they are still two different technologies and are not compatible with each other. iDEN phones will only work with iDEN networks, and GSM phones will only work with GSM networks.