This time I thought I'd make it very regex.

#!/usr/bin/perl
s/(.{4})/print (chr($c+=$1>=1000&&1000-$1||$1*1))/eg for (@_ = <DATA>)
__DATA__
0106001110020001108400650013000100051012100300131082008010110013100610
+7600721007000200081006001311040002
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