On Thu, 28 Apr 2005, Matt Roth wrote: > >I do not understand what distinction you are trying to make between "PSTN" > >and "CPE". > > > The distinction I'm trying to make is between our hardware and the > carrier's. To be clear, the CPE side will be the equipment we will be > responsible for purchasing, configuring, and maintaining. The PSTN side > will be the T-1 that we order and have configured for us from the > carrier (up to the demarcation point). I looked at what was happening > on the PSTN side primarily in order to better understand the signal we'd > be receiving and how it is processed. Hopefully, this will lead to > predicting and circumventing hardware bottlenecks before they happen. > Do you or anyone else have any suggestions for terms other than "PSTN" > and "CPE"? Does it really matter? Network is symmetric. Your "PSTN" is "CPE" to carrier. So you should probably refer to those as "FXO" and "FXS".
> >http://home.comcast.net/~mroth01/T1-PSTN.gif > >Generally, you don't refer to the ulaw codec as DSP. > > > Thanks for pointing that out. I erroneously believed that the > companding occurred after the analog-to-digital conversion, on the > digital signal. After checking here > (http://en.wikipedia.org/wiki/Companding) I see that the compressing > occurs before ADC and the expanding occurs after the DAC, both on the > analog signal. Since my setup will be strictly digital (no analog > phones on our side), I do not have to worry about this. Other people > may, so for their benefit, could you explain where the �-law codec fits > into the equation, and if it is resource-intensive if it needs to be > performed on the Asterisk server? Also, should I relabel the codec as > "G.711 �-law" in my diagram? u-law is just your basic ADC/DAC. Your input is analog signal and your output is g.711 u-law stream. -alex _______________________________________________ Asterisk-Biz mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-biz
