I want to connect my cable modem to our home phone wiring. We have comcast digital voice and right now the cable modem is connected to our cordless phone and it works fine.
When I connect the cable modem's telephone port to phone jack A (inconveniently in another room) and a phone to jack B (in the same room), then the phone has dial tone and I can call out. All is good.
When I connect the cable modem's telephone port to jack B (the preferred jack), it doesn't work. Instead a bunch of the lights on the cable modem start blinking in sync. I'm not sure how to test what's different between the two, so that I can fix it if possible.
Does this make sense to anyone? Anyone have any suggestions?
The eMTA has two jacks, the 1st jack, labeled L1/L2 on many eMTA's is a RJ14 jack that supplies dial tone to two lines if you have them. The line one pair is for line one, the line 2 pair is for a 2nd telephone line of you subscribe to one. If you don't subscribe to a 2nd line, that jack still has talk battery voltage on it.
The 2nd port, marked L2 on many eMTA's is only for a 2nd line, the same as the 2nd line on the 1st port.
You can't use both jacks unless you subscribe to 2 lines. You have to use the first pair on the L1/L2 jack and that is all. This would be the center two conductors on a phone cord for tip and ring.
If you need to split the L1/L2 jack to feed both the inside phone wiring in the home and an additional phone in the room with the eMTA, you need to add a phone splitter that will give you two jacks for line 1.
Thanks for the response. I'm not sure I was clear, though. I'm using the same jack all the time, the L1/L2 jack. When I was talking about Jack A and Jack B, I meant the wall jacks in the house. I connected the L1/L2 jack to Jack A and the phones on other jacks in the house work. When I connect L1/L2 to Jack B (the preferred one), I get the bottom 4 or so lights on the modem blinking in unison.
I made the image below in case it's helpful. The red connection doesn't work and the blue one does. I don't know what the difference is between them.
Does this clarify the question? Any ideas on what could be different or how I could test for differences? Thanks again for your help.
Sorry, It would be impossible to know how your jacks are wired or miswired without physically being there, opening up the jacks and toneing out all the lines.
Make sure all inside wiring is disconnected from the telco's NID on the side of the house, so your not getting any talk battery voltage from the telco's line feeding into the inside wiring either on the first or second pair.
If you want to open up both jacks and confirm the red/green (blu-wht/wht/blu) are connected to the center pair on each jack (line 1). and that all 1st pair (red/green or blu/wht) inside wiring is connected together either at the termination point, where ever that is, (garage, outside, basement etc). Look at each jack and make sure the 2nd pair (yellow/black or org/wht) is kept on the 2nd pair and is not connected to line 1.
There are many sites on the internet that shows examples on how phone jacks and inside wiring should be connected, that might help you out.
Most likely you will need to open up at least those two jacks to look at what wires are connected.
Most of all, be careful, there can be upwards of 48 volts of talk battery on the line, and when it's ringing, it's 90 volts.