scope:

Jitter buffers and echo cancellers have a major effect on voice and data transmission quality in telecommunication networks. They affect the transmission of voiceband, data, fax, text telephones and transmission of unrestricted digital information (UDI).

Since the requirements for the settings of jitter buffers and echo cancellers differ for different services, the present document describes the activation and mode switching procedures of jitter buffers and echo cancellers, including the requirement for in-band tone activating and other control mechanisms.

The present document does not apply for fax transmissions with ITU-T Recommendation T.38 [i.8].

It is understood that the clock accuracy of all elements involved is sufficiently high for application of the present document.