[Asterisk-Users] T1 E&M vs PRI question

[Keith Burns]

Correct, CAS can supply DNIS but the call set up times are significantly
longer.

> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-
> bounces at lists.digium.com] On Behalf Of David Boyd
> Sent: Monday, January 24, 2005 7:12 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: RE: [Asterisk-Users] T1 E&M vs PRI question
> 
> Responses embedded below!
> 
> On Mon, 2005-01-24 at 18:49, Keith Burns wrote:
> > Depending on the switch they are using, there are a limited number
of
> > D-channels (or D-channel licenses).
> >
> >
> >
> > CAS signaling needs RBS (it's the winking in this case).
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: asterisk-users-bounces at lists.digium.com
> > [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Matt
> > Beebe
> > Sent: Monday, January 24, 2005 2:47 PM
> > To: asterisk-users at lists.digium.com
> > Subject: [Asterisk-Users] T1 E&M vs PRI question
> >
> >
> >
> > Ok,
> >
> >
> >
> >
> >
> > I'm about to take the plunge, and am trying to decide between
> > Channelized T1 E&M and PRI.  I'm getting an "Integrated T1" which
will
> > have data and voice capability, all plugged directly into my digium
> > single T1 card.  In either case the data piece looks pretty
> > straighforward, just setup the channel properly, hand it off to the
> > linux hdlc layer, and route away.... the voice side seems a little
> > more complex -- I'm looking for clarification and/or advice:
> >
> >
> 
> PLease no Flame, just a correction if required.
> 
> There seemed to be issue using Data/Voice on the digium cards, but I
> believe it is a setup issue not a technical limitation on the card
> itself.
> 
> 
> >
> >
> >
> > It seems to me that the major differences between the two different
> > voice delivery mechanisms (other than cost) is caller id
functionality
> > and call setup delay.  With the PRI, I'll have practically instant
> > call setup and the ability to pass CNAM (caller name) and CID
(caller
> > ID) information in BOTH directions.  The PRI will give me the
ability
> > to have additional directory numbers (typically called DIDs)
assigned
> > against my voice trunks and will provide the full ANI (automatic
> > number identification) and DNIS (dialed number identificaton
service)
> > over the PRI signalling trunk.  Each voice channel will also be 64k
> > clear channel, so I could (theoretically) provide 56k dial-in modem
> > service from the same box (anyone actually doing this?? seems like a
> > neat application for the dsp software guys)  I also lose one 64k
> > channel to signalling.
> >
> Actually DNIS can be provisioned over e&m trunking also, the
separation
> of digits is done with *'s or KP/ST. So the digiti dump would be
> something like:
> DTMF
> OH ->
> 
> 	<- Wink
> 
> 		digit dump *703727131229*8004231212*->
> 							<-wink
> 								<-Answer
> 
> The breakdown of the digits is ani + Info digits then DNIS
> 
> The *'s would be replaced with KP/ST pulses if MF.  KP start sequence,
&
> ST stop sequence.
> 
> Sorry for the crude drawing, and the disclaimer is its been 4 years
> since I have looked at the digit sequence for an E&M t1 :)
> 
> >
> >
> >
> >
> > Sounds like the way to go, but basically the PRI ends up
> > being $100/month more expensive than the Channelized T1 E&M.
> >
> >
> >
> >
> >
> > The T1 E&M approach will still give me CID (but not CNAM???) over
the
> > in-band call setup mechanism (ie: quick DTMF tones during the wink).
> > Each voice channel will actually be 56k because it uses RBS (robbed
> > bit signalling -- not sure what its using this for, as the call
setup
> > is delivered via wink???).  As a result, this approach would also
keep
> > me from implementing a 56k dial-in modem service, but I could still
> > use an "ordinary" modem or fax dsp to provide 33.6k dial-in.
> > This setup can support DID, but its appended (or prepended,
depending
> > on the provider) to the DTMF call setup (which extends the time for
> > calls to actually connect).  Not sure if CID or CNAM can be provided
> > for outgoing calls (I think some providers can enable me to be able
to
> > wink to them the number to pass as caller id??)
> >
> I don't know of a way for outbound or inbound CNAM to be provided on a
> T1 unless you are using SS7 or some like control protocol.
> 
> The setup time is in milliseconds for PRI and potentially could be 1.2
> seconds in E&M including wink times, and outpulse dump. This can be
> decreased if the carrier can accept fast outpulse, and also be
decreased
> if you use MF with KP & ST pulses instead of DTMF.
> 
> Robbed bit allows for the current channel condition to be maintained
in
> the signalling stream. When a channel hangs up the onhook condition
has
> to be able to be passed to the other end of the t1 for disconnect.
The
> wink and digits dump at the start of the call only provides call setup
> capability.
> 
> >
> >
> >
> >
> > I believe in either case, the normal call features (3-way,
forwarding,
> > etc) can be provisioned.
> >
> >
> Additional features are usually  handled within the switching/* system
> once the call has been setup. There are some features that are
available
> via ISDN, however in my experiences most carriers don't/won't support
> them.
> 
> >
> >
> >
> > Do I have it about right??  Is it pretty normal for providers to
> > charge a premium for the PRI?  Any thoughts/clarifications to my
above
> > assumptions??  Are there other pros/cons of each setup?
> >
> >
> Yes it is normal for increased cost, however IMHO I would spend the
> additional money (assuming one can afford it) for improved throughput
> and performance.
> 
> >
> >
> >
> > Thanks in advance!
> >
> >
> >
> >
> >
> > -Matt
> >
> >
> >
> >
> >
> >
> >
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