I have a corded AT&T 993 2-line phone. Ooma Telo is Line 1, Comcast VOIP is Line 2. The line on which I'll be using Ooma was previously Vonage. Ooma is set up as follows: modem > Ooma > router (Netgear WNDR3400). Phone is connected directly to Ooma Telo
When I pick up and start dialing I hear a buzzing sound. This happens on both lines (Ooma and Comcast). If I disconnect the Comcast line the buzzing on the Ooma line goes away. If I connect Ooma and Vonage, the buzzing is still there. If I disconnect Ooma and go back to Vonage and Comcast the buzzing isn't present. In other words, whenever Ooma is connected, there is a buzzing on both lines (i.e., either Ooma and Vonage, or Ooma and Comcast). There is no buzz if I connect Ooma to a single line phone.
Home phone lines are disconnected from the telco box in the basement.
I've switched out all cables (phone and ethernet). I've tried setup as modem > router > Ooma. I've moved the Telo away from the phone. I've moved the Ooma power plug to numerous other electrical outlets. I've tried using Ooma on both line 1 and line 2 on the AT&T phone. I've installed a telephone line filter to the Ooma line before it gets to the phone. I've installed the filter to the Comcast line before it gets to the phone. All without success.
Per Speedtest.net: Download speed is consistently 15-20Mbps, Upload is 3.75+ Mbps
Whether it would happen with Comcast & Vonage would depend on many things; could go either way.JoePort wrote:That would be too bad. Wouldn't the same thing happen when I use Comcast on one line and Vonage on the other?
How can I tell if the phone isolates the lines?
One thing you can try, with a small but nonzero chance of success, is to turn the power supplies 180 degrees in the sockets. That is, the Ooma for example has a wall-wart power supply, and without knowing I assume the Comcast has one too. Each of these plugs into the wall socket, and may be able to be plugged in two ways (some will go in only one way). Try every possible combination of positions. As I say, this has only a small chance of success, but costs nothing to try and can do no harm.
Another thing you can try relates to the fact that the connection from Ooma to your 2-line phone is two wires (one pair); the same is true of the connection from the Comcast device to the 2-line phone (another pair). If you have a way to swap the wires within each pair, that's worth a try too. The most likely place to find this possibility is inside the 2-line phone. The older it is, the more likely that you can swap the wires inside the phone, because in old phones they will be on screw terminals inside. Avoid swapping wires between the two pairs! Swap them only within a particular pair. If the phone is old enough, the wires will have screw connections inside the phone and be easy to swap, and probably one pair will be red-and-green, and the other pair black-and-yellow. This, too, has only a small chance of working, but it's possible.