For 1.6.0 and 1.6.1 the same patch should be OK:
rtcc-1.6-179325.diff or rtcc-1.6.diff
This version also includes the code cleanup from bug 14503 as there are sometimes crashes accessing the config ... probably after the backup_copy magic
The latest (old V1) version is rtcc-1.4-111390.diff or rtcc-1.4.diff
The latest Curl version from Grey Man is rtcc-curl-1.4.18.1.patch or rtcc-curl-1.4.patch
New version V2 is available rtcc_V2-1.4-130949.diff or rtcc_V2-1.4.diff
The new version (V2) is not compatible with V1, because of the changed variable names - now RTCC prefix is used instead of LIMIT_RECHECK. See 'core show application Dial' for exact variables names and meaning.
This new version uses just a single thread for processing all calls instead of separate thread for each one.
Fixed a bug with attended transfers after 113648
Examples of usage and some notes can be found here Readme.txt