Tracing phone cable from external connection box to master socket

[#1]

Hello tech folks! I'm trying to see if there is a relatively straight forward way to trace a phone cable from the external connection box (image attached) all the way to my master socket. 

The distance between the external box and my master socket is fairly large, and it doesn't seem to be running on the exterior. Tacking a peek into the external box I can see the underground wiring coming in via the trunking you can see in the image, connecting with some crimps, and then exiting the box upward and internally into the wall cavity. 

I am hoping it's routing upward, between the ground and 1st floor, and back down a cavity/chaser to the master socket. I'm a little worried it might also be routing under the ground floor.

Does anyone know of a way to figure out where that cable might be being routed?

Thanks!

[#2]

@jakeisonline  Welcome to the forum.

Take off the front section of the master socket, you may need to renove two screws. Next very carefully (note that you are not supposed to do this so may be charged for the rectification if you pull wires off), undo the back section from the wall/pattress box and you may be able to see whether the cable disappears into the wall in an upward or downward direction.