Few additional informations about this 3CXPhone release: Bugfixes - Bug described as "Bug fix in audio sound device detection". It refers those audio devices having some blanks appended to their names, such as C-Media USB Headphone Set, issue which affected their proper use due to preferences saving/restoring (bug complete description here http://www.3cx.com/forums/audio-devices-aparently-not-saved-on-3cxphone-exit-16423.html ) - Bug described as "Bug in recording when pbx sip port is not default" refers the case when when the PBX is specified as addressort. PBX is part of the local recording filename, therefore the ":" - not allowed as a character in OS filenames - denied proper file creation, reading and UI filtering. Automatic early media detection The most significant feature is automatic early media detection; from now on, the old "suppress early media" option is no longer needed and was removed from Preferences dialog. Early media is the sound provided by remote (called) party before call being established, most commonly a ringing tone. However, some providers replace this ringing tone with announcements. With the previous version of 3CXPhone, this early media could be heard either mixed with local ringing sound (supression off) either muted (suppression on). Starting with this release, local ringing sound will be stopped when early media is detected, leaving only this one to be heard. Audio recording in stereo MP3 format A new feature is optional recording in stereo MP3 format. Stereo means one partner is heard on the left speaker, the other one into the right speaker. In this way, not only a real-talk effect is produced but, depending by audio player, you may select one or another channel to listen more clearly. The MP3 format allows a smaller filesize fo recording, but also adding of some extradata ("author", "title" ansd so on) in the ID3V1 header, useful in case you prefer to add them as a list in a dedicated MP3 player such Winamp.