Still having problems with Diamond not ringing

[akates]

I've had this problem with 1 touch pro and now 2 diamonds so I really don't think it's my particular handset but I have no idea how to fix it. Occasionally when people call me it rings 4-5 times on their end and then goes to voicemail without it ever ringing on my end. This isn't the problem where the ring is delayed but the flashing starts immediately, it never flashes or rings period. Sometimes I won't even get the voicemail notice until I make an outgoing call. Once I make an outgoing call then incoming calls work fine, it's just like it looses the ability to receive calls sometimes and I need to make an outgoing to wake it up. This is with it both in standby and not in standby mode and I just can't figure it out. I don't believe it's a signal thing because while I only have 1-3 Ev bars, when a call comes in or goes out I have 5-6 1x bars. It even happens on roaming. I've already set my tower delay from 2 to 1 and that hasn't helped. It either rings on my end on their 2nd ring or it never rings at all. Any suggestions as this is driving me nuts!!