http://tomeko.net/software/SIPclient/g729_bc/
tSIP softphone G.729 codec plugin, based on bcg729.
Built with Code::Blocks 16 (version matters).
Installation: copy g729.dll to tSIP/modules folder, restart tSIP, enable G.729 in tSIP Settings/Codecs.
If you are distributing this plugin with tSIP then according to some interpretations you might need to relicense tSIP to GPL v3, but IANAL. You could also request proprietary license from Belledonne Communications.