All lines also end with 9 or zero---also, there are several sequences that repeat.
11213001213110, 0102715, etc.
It is no standard encryption---no special characters or letters. Even simple reversible Cisco level 7 passwords have letters in them. I would guess that all numbers or sequences of numbers correspond to letters. To separate them, he probably uses zero or one, to indicate the beginning, end, or separators.
This is important, because for example---several instances of 112, and a few of 1112---but why not 1112? Because the first one can be assumed that it is the last number of the previous sequence. This indicates that perhaps the code is three digit numbers, each corresponding to one single letter. Or...any number that is higher than 6 does not belong to a pair of numbers---take them all out of the equation, and what is left? Just thinking out loud. The ones and nines that each sequence begins and/or ends with is throwing me...but this seems to be his own code---a bunch of repeating sequences, all sequences begin with 0 and end with 9 or 0, and no letters or special characters.