V.42bis is a data compression method found in modems. It has also
been specified for GPRS as data compression algorithm.
The implementation has been taken from IAXmodem:
https://sourceforge.net/p/iaxmodem/code/HEAD/tree/
svn checkout svn://svn.code.sf.net/p/iaxmodem/code/ iaxmodem-code
Revision: r36
Change-Id: Iabedece9f97ca944a1e3f747bb073e532c4e9dca
