diamond radio keeps on restarting after call

so i make a call and when i try to make another call right after the radio seems to restart i can see the icon were my bars are with an x then get signal again, always happens when i try to make a call right after i hang up the previews call. its really started to annoy me couse i have to wait like 30 second to make another call. i have the sprint diamond with the ssk 2.7.5 rom, but it happens with other roms too. is there a fix to this or am i just screwed