The Mistery of The cave

They found the mystery of the cave. First chapter.

-"Can you find the meaning?"
-"I can make a try." I answered, " But there is no guarantee."
" That's enough", Mr Jones smiles, " I know, your success rate is 100%."
After some casual words exchanged, Mr Jones told me, "We'll meet again in the morning at the airport.
-"Okay."
We were shaking each other's hands. Mr Jones left the room happily.

***

I am a professional detective.
Me. Jones and his friends discovered a cave on a time of an adventure.
On his stone wall, they found, all English capital letters with a mobile number. They weren't sure, that was just a mobile number or not. Because, mobile didn't work in the cave, as well as the entire valley area. No people lived there. Locality is far away from the place. Then, who wrote those? They just understood they are civilized people, as they know English well.
To discover the rest, they hired me.