G.729 has been extended with various features, commonly designated as G.729a and G.729b: Dual-tone multi-frequency signaling (DTMF), fax transmissions, and high-quality audio cannot be transported reliably with this codec.

This is incorrect as G729a is an alternative method of encoding the audio, but still generates data decodable by either G729 or G729a - i.e. there is no difference in terms of codec negotiation.

G.729 has been extended in Annex B (G.729b) which provides a silence compression method that enables a voice activity detection (VAD) module.

It also includes a discontinuous transmission (DTX) module which decides on updating the background noise parameters for non speech (noisy frames).

It uses 2-byte Silence Insertion Descriptor (SID) frames transmitted to initiate comfort noise generation (CNG).

By inserting comfort noise, analog hiss is simulated digitally during silence to assure the receiver that the link is active and operational.

[6][7][8][9] AIM IP LLC, a California Limited Liability Company based in Mission Viejo, CA[10] filed 17 patent infringement lawsuits[11] in the Central District Courts of California accusing 22 different companies, including, Cisco Systems, Polycom and others of infringing U.S. Patent No.

[16] In 2010, the '853 patent was sold by Conexant Systems to AIM IP LLC, a California Limited Liability Company based in Mission Viejo.