The users can share documents in real time, can collaborate on applications and exchange information instantly around the world. The technical challenges for Internet Telephony are many. Fortunately many of these challenges are being resolved as communications technology improves and more bandwidth becomes available to the users. Some of the significant challenges are discussed below. On the Internet, packets do not follow the same path.
Human brains can reconstruct some of the information that is lost in packets.
The voice quality at zero packet loss is termed as ITU quality 5. Various techniques such as Silence Substitution, Packet Repetition, Noise Substitution, Packet Interpolation, Frame Interleaving and Forward Error Correction are used to account for packet loss to some degree. In voice communications, the basic guideline is that delays of below 150 ms are acceptable. As delays exceed 150 ms, users start to run into echo and step on each other s speech. Delays between 150 and 400 ms are still acceptable for long distance communication such as ones that use two geosynchronous satellites.