Hi,

Are there any products out there which support Modem over IP
protocols. The only one that I could find was CISCO's Access Server,
but is it compliant with any standard or is it based on CISCO's
proprietary technology ?

Are there any standard compliant products out there ? Any
help/pointers would be most helpful.

Sachin

The term "Modem over IP" encompasses a multitude of sins.

Most commonly this will be just "modem passthrough", which
means that the modem tones are simplemindedly carried in a 64k
stream (G.711 or G.clear codecs) with echo cancellation and
voice activity detection turned off.
http://www.cisco.com/univercd/cc/td/...3/dtmodptr.htm

There is also "modem relay", whereby the modem data is demodulated
by the DSPs at the edge of the voip network, so that only the data
payload needs to be carried thru the IP net. See
http://www.cisco.com/univercd/cc/td/...1/ftmodrly.htm
I believe that this is a Cisco-proprietary scheme.
The ITU was working on a standard for this ("V.MoIP"),
but I haven't heard any news on this lately.

Here's a pretty good whitepaper on the top from Mindspeed:
http://www.mindspeed.com/web/downloa...ode=attachment

Aaron

---


~ Hi,
~
~ Are there any products out there which support Modem over IP
~ protocols. The only one that I could find was CISCO's Access Server,
~ but is it compliant with any standard or is it based on CISCO's
~ proprietary technology ?
~
~ Are there any standard compliant products out there ? Any
~ help/pointers would be most helpful.
~
~ Sachin

Aaron Leonard <Aaron@Cisco.COM> wrote in message news:<bta0rvkmfvp46ljk8bkqi3f3c1q0ud3qnd@4ax.com>. ..
Aaron,

Thanks for the links and useful information. The approved standard for
MoIP is V.150.1 and CISCO's documentation gives no hint of whether it
is V.150.1 compliant.

Even for the Modem Passtrhu mode - CISCO doesn't mention whether their
scheme is standard compliant or not.

Sachin

On 10 Nov 2003 23:39:08 -0800, scngupta@yahoo.com (Sachin Gupta) wrote:

~ Aaron Leonard <Aaron@Cisco.COM> wrote in message news:<bta0rvkmfvp46ljk8bkqi3f3c1q0ud3qnd@4ax.com>. ..
~ > The term "Modem over IP" encompasses a multitude of sins.
~ >
~ > Most commonly this will be just "modem passthrough", which
~ > means that the modem tones are simplemindedly carried in a 64k
~ > stream (G.711 or G.clear codecs) with echo cancellation and
~ > voice activity detection turned off.
~ > http://www.cisco.com/univercd/cc/td/...3/dtmodptr.htm
~ >
~ > There is also "modem relay", whereby the modem data is demodulated
~ > by the DSPs at the edge of the voip network, so that only the data
~ > payload needs to be carried thru the IP net. See
~ > http://www.cisco.com/univercd/cc/td/...1/ftmodrly.htm
~ > I believe that this is a Cisco-proprietary scheme.
~ > The ITU was working on a standard for this ("V.MoIP"),
~ > but I haven't heard any news on this lately.
~ >
~ > Here's a pretty good whitepaper on the top from Mindspeed:
~ > http://www.mindspeed.com/web/downloa...ode=attachment
~
~ Aaron,
~
~ Thanks for the links and useful information. The approved standard for
~ MoIP is V.150.1 and CISCO's documentation gives no hint of whether it
~ is V.150.1 compliant.

Wow, I wasn't even aware that V.MoIP had been ratified by the ITU.

I've done some research and can state that we do not yet support
V.150.1 modem relay.

~ Even for the Modem Passtrhu mode - CISCO doesn't mention whether their
~ scheme is standard compliant or not.
~
~ Sachin

Sure, our modem passthrough implementation is "standard compliant", not
that I'm aware of any standard per se for modem passthrough. I.e.
just use G.711 (u-law or a-law) over RTP with your echo cancellers disabled,
VAD turned off and static jitter buffers. RTP redundancy if used is
given in RFC-2198; DTMF is encoded in RTP per RFC-2833.

Modem detection is triggered a la E.164 by sensing the V.25 ANSam.

Aaron

Aaron Leonard <Aaron@Cisco.COM> wrote in message news:<tih2rvo7nshcfmq541010lhndnpngmn1q9@4ax.com>. ..

<snip>

Thanks. That solves a lot of my problems.

Thanks for this. I will look up in the required specifications.

Thanks Again,
Sachin