If so, just unplug the modular plug(s) and that should disconnect your house wiring from the telephone company.
Then just connect a phone cord from Telo's "phone" port to a walljack.
For further info: viewtopic.php?t=13354
My description is not that clear in the previous posting. So I took a picture of the NIB box. One thing I forgot to mention is that there was an alarm system hooked to the phone, and it has not been in use for a while. I will see if i can post the picture here. I am a newbie.
Here is what I think you have: dedicated wire from NIB to alarm (RJ31X) delivering telephone company dialtone to alarm panel then back to NIB on 2nd pair; then this 2nd pair is connected back to the house wiring.
More on this type of wiring: /viewtopic.php?f=2&t=12131&start=30#p92717
Here is what I see Looking at the pic you posted, you got 3 wire bunches sticking up to the right of the NIB.
The most left wire bunch is coming from the telephone company, feeding to the most right wire bunch going into the alarm on pair 1 and then returning the telephone company dialtone on another pair feeding the house wire bunch in the middle (thin gray wire bunch).
This is all you need to do: un-connect (by cutting) all the wires that are connected together and leave yourself with all the wire bunches isolated, not connected to anything. This will isolate your house wiring and you'd be able to safely distribute your Ooma dialtone by connecting Ooma's "phone" port to a walljack.
You can cut the wires coming out of a wire bunch into same length, make sure no metal leads (cut the metal leads off if any). Get the wire bunches into the NIB through the hole on the bottom and then close the NIB. Optional, you can curl the wires and make them look neat by wrapping the wires around a pencil like so: