@JWRacedog: The phone systems work during the day time but around sundown calls start to drop, sometimes we get 5 seconds of talk time, sometimes we get 45 seconds of talk time, it's completely random. Then around sun up, the phone systems work perfect. We actually saved a good amount of money so I'd really like to stay with them.

@Lightninghorse: I just checked with TWC tech support, call waiting is already disabled on all lines. Also they don't know the voltage on the lines but they know its transmitting at "48 decibels"

@fifty5footer: The calls arent routed differently based on time, to the best of my knowledge. All calls go to the front desk regardless of time unless they turn on night mode, which has always been off. I'm going to try a test by changing the time on the switchboard to 3:00AM and see if calls start dropping. If they do then I'll know its a problem on my end for sure.

@EV607797: I'm not sure about the ground/loop start trunks, but since its working during the day time it shouldn't be a problem with that right? I'm not sure about voltage but according to TWC tech support they are transmitting at "48 decibels"

When the phones are working correctly during the day I'm going to change the time on the switchboard and see if that has any effect (in case its routing the calls differently during night time). If it starts to drop calls after I change the clock on the switchboard I'll assume its a problem on my end.

One last thing to note, we have internet and phone with TWC, internet always works fine but phones have problems (only at night though)

I'll keep you guys updated, but if you guys can think of any other reasons this may be happening then please let me know. Thanks so much for all your help! Have a great thanksgiving!