My understanding of the T-1 TDM and the PSTN side is pretty solid, as itYou are severely confused, using wrong terminology, so it is very hard for us to understand what exactly you are trying to say and what you are asking.
is mainly based off of Intel Corporation's T1/E1 Technology Primer (see
Sources), but the CPE side is largely deduced from what I knew about the
PSTN side. There may be holes or mistakes, so I would appreciate any
corrections or additions that you can offer. Specifically, I would like
a detail of the TDM - VoIP conversion process, similar to the basic T-1
TDM one I provided.
Now, be gentle.
What someone is missing, is that TDM and VoIP aren't "converted." TDM PRI's include signaling in the same bitstream. VoIP uses separate data paths for signaling and voice. The voice data can be the same, or different.
Agreed. But not to him. T1 refers to the line coding on 2 physical pairs of wire to encode and carry a 1.544 Mbps datastream. T2 is four of those signals multiplexed onto 2 pairs of wire. T3 is 28 DS1's (7 DS2's) multiplexed onto two coaxial cables. DS1 is a logical concept that defines what to do with that signal, what the bits mean; each DS1 is made up of 24 DS0 time slots. An ISDN PRI is the definition that one uses 23 of the time slots for 23 voice channels, plus one DS0 dedicated to signaling. A DS3 is 28 DS1's (and is usually carried on a T3 physical layer, does it begin to make sense?)The differences between a T-1, DS-1, and ISDN are subtle and notThey are not subtle and they are very clear.
universally agreed upon. For a discussion of these issues see the
following links:
It's too bad. A lot of people without any telephone background try to make up stuff using pieces of the old terminology and wonder why they stay confused. They could look it up, but they don't. For instance DID's. DID has a specific meaning and inward service from the PSTN handed off on VOIP isn't it.What's the diff between a T1 and a DS1Don't try to gain knowledge from web forums, you'll only become dumber, it
(http://pbxtech.info/showthread.php?t=1100) PRI setup
(http://pbxtech.info/showthread.php?t=1250)
is like learning about hosting by reading WHT. I feel dumber already after
reading those posts.
There's no difference. DS1 is a standard signaling with 1.54Mbps rawNot quite. See above. T1 is the physical interface, DS1 is what you carry on it.
capacity. T1 is a product name for DS1 by your carriers. PRI is "primary
rate ISDN" which is DS1 partitioned into 23 "Bearer" channels for calls,
and one "Data" channel for ISUP call signaling.
- Is my understanding of using the same codecs and signaling protocols
on both sides of the Asterisk server in order to circumvent transcoding
and conversions on the server correct?
Yes
- Are there any other host-intensive processes that I should consider
offloading to the gateway, such as echo cancellation?
Yes, echo cancellation.
- What does the PCM µ-law codec used in T-1 multiplexing map to in termsYes, PCM u-law codec is exactly the same as G.711 ulaw.
of Asterisk codecs (G.711 µ-law, perhaps)?
And outside of North America and Japan, a-law is used.
No. It writes data to whatever format the sound card supports, usually 16 bit linear (raw) which becomes .wav if you add file headers to it.
- What codec does the Monitor application use when digitally recordingI *believe* that it will write the data in G.711 format. Don't rely on this though.
calls (if possible, I would like to avoid transcoding the streams when
recording and let sox handle the conversions on a different box)?
-- David Josephson _______________________________________________ Asterisk-Users mailing list Asterisk-Users@lists.digium.com http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
