Nextel i560 out calls troubleshooting

[mueks]

Hey there, well i got a motorola i560 and the cellphone was rlly good looking, no scratches and even if it was an used cell phone, it appears that the original owner just used it a few times.
I brought a brand-new sim card because i lost my old phone (a motorola i880), then i inserted it in my i560, i could make direct connect, signal was pretty bad at the start, but now it has nice quality, but i can't make normal cell phone calls! i tried to call home, another cellphone, friends' homes, and even another nextel number, but i just can make direct connect, send alerts and recive alerts!
I asked to the technical support guy in my town and told me it's normal in new sim cards, he explained me that the sim card has to adapt to the new phone and that i've to wait for a while (3-4 days so far), after ask him i consulted google and i found a guy with the same trouble, but he got no answers or advices, well... i want to discard if it's an hardware problem and know if i should believe it's normal and wait a couple of days for see results or if i'd try some software modification, like firmware and stuff.

can some1 help me???