Hum on the phone; Customer Support not so hot
As another purchaser said and retracted, I also had a hum on the phone when BOTH lines (copper and VOIP) were plugged into the phone. When either line was plugged into the phone individually, it sounded fine. The 993 has a great feature set for the most part. My biggest complaint other than the hum is that the volume control does not seem to control the headset jack.

I called AT&T customer service about the humming and, after, many questions from a script, I was told to change the channel on my router as that was probably interfering with my CORDED telephone. The change had no effect which is what I expected but I wanted to give the "tech support" folks a chance.

I would not recommend this phone to users having VOIP/copper wanting 2-line service. I will be returning it to Amazon and look for a Panasonic locally.

Great phone for price
I bought this as a gift for my parents who needed a two line phone. So far, phone has been great. Easy setup, sounds wonderful. My parents don't really need (or use) any advanced features, so for a simple two line phone with call display, it's perfect.

Not bad, but room for improvement. VoIP issue is fixable!!
Pros;
1. Price,
2. Two line,
3. Decent display, (but see below),
4. Large area to write names for speed dial,
5. Decent sounding speakerphone, though 'tinty',
6. Battery backup for power failure, but time still has to be reset,
7. Auto busy redial: keeps on dialing every 30 seconds if line is busy (a rare feature),
8. Fairly large footprint, but not too big.

Cons;
1. New call indicator can't be turned off. Even if you answer the call on this phone, indicator still lights. I solved this by putting a small piece of electrical tape over the surface mounted LED on the circuit board for each line.
2. Display backlight is dim,
3. Base isn't angled up far enough. I cut a 1x2" piece of wood to prop up the back of the base so the display can be seen easier.

This VoIP issue with the hum should be fixable. It is just a ground loop, fixed by reversing the two wires from your POTS line. This worked for me!

Nice
The price and function of this phone is what I was looking for. I currently have a land line phone AND a magicjack- the internet phone - attached. It has all the features that I was looking for. The buttons are easy to use.
The one downfall, in my opinion, is you must have the display light turned on at all time to easily see the incoming caller ID. In previous phones I have had, that area will light up when there is an incoming call, not stay lit all the time. I feel like I am wasting energy~~small amount that it might be.
But I would recommend to anyone that is looking for an inexpensive two line phone.

AT&T 2 Line Corded Phone
If you want a very professional looking phone for you home or office I think this one is great. It has eveything you need in a phone. The price of phone was good, it best to buy a quality product than something worthless.