Hi,
R2 Signalling basically has a lot of variants. It usually varies from country to country. It has a lot of names like R2, R2 modified, CSMF (Compelled Sequence MF), R2MF, MF etc… (But not sure about C2).
A detailed description of signals are available on the following websites….
http://www.pulsewan.com/data101/cas.pdf
http://www.pulsewan.com/data101/cas_basics.htm
http://www.sunrisetelecom.com/technotes/TEC-GEN-2B-MFCR2.pdf
Hope this helps.
REgards.