[nsp] as53xx SIP and DSP

[Knudson, Eric]

Thomas,

Though g711ulaw/alaw is what's received on the tdm link, if you do anything other than hairpin it, you're going to use a dsp. If you use g711ulaw/alaw as a codec to xmit packet data, you'll use a dsp (even though there is no compression, you still need a dsp to packetize the voice data). 

I have heard something similar about the TCL IVR though, but haven't had any experience with it to comment though; sorry. 

Eric


-----Original Message-----
From: ewc at axelero.hu [mailto:ewc at axelero.hu]
Sent: Thursday, January 15, 2004 6:12 PM
To: Knudson, Eric
Cc: cisco-nsp at puck.nether.net
Subject: Re[2]: [nsp] as53xx SIP and DSP


Hello Eric,

thank you for fast response!
I thought about it and in theory it won't need DSP while voice on ISDN
is already a 64kbps PCM data stream and I can choose the right
outbound codec (hmm) - g.711 alaw or g.711 ulaw. So a signal processor
has no job with this.
But as I wrote, it is in theory. Cisco may have it differently [or my
speculation could be wrong also].
Somewhere I read around TCL IVR, that the reason Cisco can use only
g711 for voip inbound calls with IVR (I mean the IVR application is
running on voip peer), because it can't allocate DSP resources for
encoding.
I could be totally wrong...

Thanks,
        Thomas

Friday, January 16, 2004, 12:52:17 AM, you wrote:

KE> Thomas,

KE> You're encoding the tdm-voice to packet data, so, yeah,
KE> you'll need dsps. If you're doing TDM switching (like bouncing a
KE> call out another ISDN PRI from the gateway) then there's no need
KE> for a codec, or dsps.

KE> Eric


KE> -----Original Message-----
KE> From: cisco-nsp-bounces at puck.nether.net
KE> [mailto:cisco-nsp-bounces at puck.nether.net]On Behalf Of ewc at axelero.hu
KE> Sent: Thursday, January 15, 2004 5:01 PM
KE> To: cisco-nsp at puck.nether.net
KE> Subject: [nsp] as53xx SIP and DSP



KE> Hello,

KE> is there a need to have DSPs (VFC cards) for making this:

PSTN --->> Cisco 53xx ---> G.711 SIP or H.323 --> another gw
KE> PSTN <--- Cisco 53xx <--- G.711 SIP or H.323 <-------+

KE> On Cisco 53xx (or 5400) should be no IVR configured, just incoming and
KE> outcoming dial-peers.

KE> I read on cisco.com, that TDM switching works woithout DSPs, but it
KE> was not clear if the asked configuration will work also.

KE> Thanks in advance,
KE>         Thomas