Panasonic KX-NT511L Guía De Referencia Rápida página 4

Información importante
The Use of IP Networks through the PSTN
R Internet Protocol (IP) by its nature introduces delay into speech signals as each data
packet is formulated and addressed. Telecom Access Standards recommends that
suppliers, designers and installers using this technology for calls to or from the PSTN
refer to ITU E Model requirements in the design of their networks. The overall aim is to
minimize delay, distortion and other transmission impairments, particularly for those calls
involving cellular and international networks, which already suffer extensive delay.
Echo cancellation
R Echo cancelers are not normally required in the Telecom PSTN because geographic
delays are acceptable where CPE return loss is maintained within Telepermit limits.
However, those private networks making use of Voice over IP technology are required to
provide echo cancellation for all voice calls. The combined effect of audio / VoIP
conversion delay and IP routing delay can cause the echo cancellation time of ³ 64 ms to
be required.
4