I had 2 phone lines coming into house and recently cancelled 1. I would like to rewire cancelled # phone jack to receive my other number so all house phones will be on the same line.I have been playing around with the switch over. I have looked at the other house jacks and tried to duplicate still not working... any ideas?

Joe go to where the two phone line enter the house, generally the phone company mounts a box on your house and brings the phone lines in from the street, open the box and join the two lines together. Also, the red and green wires are the primary phone line.

Without knowing your wiring configuration or what you are describing as a "switch box".

You need to be looking at the demarcation box on the outside of your residence.

Generally speaking, the phone company will run their drop to this box. Then they pair up the Tip and Ring conductors.

Most of the demarc boxes now use Cat5e cables. With Blue/White, White/Blue being the first pair and used for line #1.

Next is Green/White, White/Green pair for line #2.

The last pair Orange/White, White/Orange is generally used for network connections.

To marry the conductors from line two to line one simply move them to the line connector above them.

My outside box has a green and a red wire going to the main number. Then a yellow and a black wire going to another line. Do you mean remove the yellow and black wires and connect them to the yellow and black terminals of the main number?

My outside box has a green wire and a red wire going to the main number. Then it has a yellow wire and a black wire going to another terminal. Do you mean take the yellow and black wires loose and reconnect them to the yellow and black screws on the main number terminal?

Joe,

Can you post a picture of the wiring in the box?

It depends. Do you have a four wire (Green <tip 1>/Red <Ring 1> /Black <Tip 2> /Yellow <Ring 2> ) drop from the phone company on one side of the connector block and the same on the customer side?

If so, then yes. From the customer side of line two, Yellow < connect with Red> /Black <connect with Green>.

Joe connect the yellow & black to the green and red.

I have 4 wires coming to the customer side (1) Red,Green,Black and Yellow.The Red and Green had gone to the main number. The yellow and black went to the terminal below and I have a empty terminal above. (A Terminal consists of 4 screws to attach the 4 colored wires).
"Yellow< connect with Red>/Black" what does that mean?
Thanks.

I forgot to mention, I can not get into the other side of the box due to a special lock. Only the customer side.

Joe,

You do not need to get into the phone company side of the box.

From the customer side, you need to connect the yellow wire from line 2 to the red wire on line 1 (that's the ring circuit) and the Black wire from line 2 to the Green wire on line 1 (that's the Tip circuit).

Like mentioned above, just move yellow wire, connect to the red above, then move black wire from below to the green above.
Many of the outside boxes "D Mark", have RJ 11 phone plugs and jacks so you can test the Phone should you have a problem, it disconnects inside phones.
In that case you could plug both lines into a 2 way.
To correct the Line Numbers mentioned previously...
White-Blue/Blue-White Pair is line one,
Orange pair is second pair,
Green Pair is 3rd pair,
Brown is the 4th pair and is typical in Category Rated wiring and for your cat 5 for networking usually has these 4 pairs.
Then Slate(gray) pair,
Then,red/blue pair,
Red/orange,red/green/red/brown, red/slate and continues for 25 pairs, then it gets worse with the bundles, but easily color coded.