Which bottom antenna stand for what?

Hey, i just can't get figure out how to get cellular to work on the used iphone 5 that i've just bought. I've replaced the antenna that i've circled in red in the picture. The old one was clearly broken, but I still have cellular problem.

Is the blue circled antenna is playing a role with cellular ? If i remove it, my problem stands the same. My phone receive signal but just can't send/receive calls/sms. Do I have to try to replace this piece? What does it do actually ?

Thanks !