Ok so i just spent all night setting a verizon s5 and i got most everything to a basic S5 with full functions, for T Mobile since i have a t mobile sim, set your phone to "Network Mode" to "Global" then set your APN to fast.t-mobile.com not epc, for some strange reason epc does not work! atleast for me in NYC. and the rest your settings you leave out execept for the MMSC "http://mms.msg.eng.t-mobile.com/mms/wapenc" now just wait for the phone to reconnect to the tower and you should have full LTE, now for MMS here is the tricky part i think ppl are not getting, DONT USE MESSAGE+ the red icon on the buttom, use the NATIVE TEXT MESSAGE CLIENT, its in the menu under messages. Message+ seems to be some type of verizon software and it will work with basic text but MMS seems to fail everytime!
now to remove that annoying unknown sim error message, you have to root your phone, no way around it! cause the software that error comes from is called "setup wizard" not the one with the android icon! now with that being said, root your phone, download TI BackUP and just freeze ALL THE VERIZON SOFTWARE INCLUDING Setup Wizard that will get rid of the annoying software and its pops from your sight!, and presto you have a fully functioning S5 without the annoying VZ goodies
and dont complain its alot of work cause your the only one that benefits from it, i spent hours perfecting my Verizon S5 and love it!
ill see if i can post the steps more in details later as am at work and try to help as much ppl as i can.