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-----Original Message----- Bob, from the user's perspective delay and not jitter is the major quality factor. Delay above a certain point required echo cancellers or the echo can be very disconcerting. In TDME systems (like ATM for example), the device converting packets or cells back into voice has a de-jitter buffer to account for delay variation in the network. The level of jitter is generally much lower than the average delay that the packet sees due to propogation. In any case, the worst case jitter drives the size of the de-jitter buffer and adds a fixed delay to the voice signal in addition to the propogation delay. I will try to find out some from of my old voice buddies at what delay the echo-cancellers become mandatory. Note: such cancellers are in all of the networks anyway due to voice trunk delays for longer distance
conversations. [ The VOIP folks
have far lax RTT requirements without echo cancellation equipment. It is
somewhere in the range of 200-400ms. However, the toll
quality voice folks have this value between 6-20ms without
using echo cancellation equipment. Vinay > "Robert D. Love" wrote: > > One of the 802.17 objectives is the propagation of voice
traffic. Are there > any hard requirements or guidelines as to how much jitter can be
tolerated by > the voice traffic without degrading the conversations? > > Any insights you can provide for this question would be
appreciated. > > Thank you. > > Best regards, > > Robert D. Love > President, LAN Connect Consultants > 7105 Leveret Circle Raleigh, NC 27615 > Phone: 919 848-6773 Mobile:
919 810-7816 > email: rdlove@xxxxxxxx
Fax: 208 978-1187 -- Michael Takefman
tak@xxxxxxxxx Manager of Engineering, Cisco
Systems Chair IEEE 802.17 Stds WG 2000 Innovation Dr, Ottawa, Canada, K2K 3E8 voice: 613-254-3399
cell:613-220-6991 |