Help Outgoing and Incoming calls not working!

[PineappleSalad]

I've had my Droid for two months now, and I've never had a major problem until now. Every time I dial an outgoing number, it apparently connects to the line I'm trying to reach, but I can't hear their phone ringing, I can't hear the numbers being dialed, and worst of all, I can't hear their voice! When I speak, all I hear in my ear is my own voice talking back to me. Also, incoming calls are not working. I can reach my voicemail just fine, and people can leave me voicemails, but there is no ringtone when people call. I don't have a missed call notification or anything, just a voicemail message. I shut my phone off completely, and then rebooted it, but that didn't fix anything. I thought it might have been due to my battery being low, but it's now at 100% and still not working. Anyone have any advice one what else to try?