Hi Jason, Thanks for the information, what router/ interfaces are you using?
Thanks! On Fri, Mar 12, 2010 at 1:04 PM, Jason Granat <j...@slash128.com> wrote: > Hi Otto, > > > > Thanks for the advice. In your second paragraph the opposite was actually > the case. The E1 voice-ports were originally showing a-law, and had > distortion. I hard set u-law on the E1 ports between the gateway and PSTN > router and the distortion went away. Perhaps that is what you meant? > > > > I took a look at the link you included. I’ll have to do some testing but my > main question is how is this handled in the real world at the provider > level? > > > > Thanks, > > > > Jason > > > > *From:* Otto Sanchez [mailto:o...@ipexpert.com] > *Sent:* Friday, March 12, 2010 4:59 AM > *To:* Jason Granat > *Cc:* <ccie_voice@onlinestudylist.com> > *Subject:* Re: [OSL | CCIE_Voice] PSTN Call Distortion Between T1/E1 > > > > Hello Jason, > > E1's and T1's will always use a-law and u-law companding mechanism > respectively, this is used to give more "resolution" to low voice > frequencies when digitizing an analog signal (the mechanism is also used in > the other end for digital to analogue conversion), each mechanism is > designed exclusively to work with its voice digital standard and cannot be > used conversely, > > In that sense, my guess is that before applying that command in your E1 > port, the companding type was u-law, you can verify this using the sh voice > port command (perhaps the default configuration of a-law was somehow > overwritten by a cptone command in the same port configuration), and when > you hardcoded the a-law companding type everything worked as expected, > > I also found a note in the Cisco IOS Voice Port Configuration Guide, which > says that the command is used when cross-connecting in a local router, > > > http://www.cisco.com/en/US/partner/docs/ios/voice/voiceport/configuration/guide/vp_cfg_digital_vps_ps6441_TSD_Products_Configuration_Guide_Chapter.html#wp1009871 > > > HTH, > > On Thu, Mar 11, 2010 at 2:37 PM, Jason Granat <j...@slash128.com> wrote: > > So I’ve got this partially figured out. It had to do with the compand-type. > E1 was a-law and T1 was u-law. I set the E1 side for u-law and it sounds > correct now. > > > > The final thing I am trying to figure out is how to ‘trans-compand’ (if > that is the correct term) on the PSTN gateway. As it sits I had to change > the compand-type between the PSTN and E1 gateway. I don’t have experience > with foreign connectivity so maybe this is the way it is done in the real > world but I am thinking that perhaps the E1 site may not want or be able to > change their compand-type, so can it be changed at the PSTN level between > a-law and u-law locations? > > > > Thanks, > > > > Jason > > > > *From:* Jason Granat > > *Sent:* Thursday, March 11, 2010 9:46 AM > *To:* <ccie_voice@onlinestudylist.com> > > *Subject:* PSTN Call Distortion Between T1/E1 > > > > Perhaps this is something simple that I am overlooking but I have the > generic setup running in my home lab with 3 gateways and one PSTN router. 2 > of the gateways are T1 and one is E1. The PSTN router is also running CME > with a 7960 to simulate PSTN destinations. Calls from any site to the PSTN > phone are fine. Calls between T1 sites are fine. Calls between T1 and E1 > sites are distorted, like the gain is way too high. I tried playing with the > gain on the voice-port but no luck. I’m not finding much online or in Cisco > docs. Any suggestions? > > > > Thanks, > > > > Jason > > > ------------------------------ > > > > http://slash128.com > > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > > > > -- > Regards, > > Otto Sanchez > CCIE #25592 (Voice) > Support Engineer - IPexpert, Inc. > URL: http://www.IPexpert.com <http://www.ipexpert.com/> > > ------------------------------ > > > http://slash128.com > -- Regards, Otto Sanchez CCIE #25592 (Voice) Support Engineer - IPexpert, Inc. URL: http://www.IPexpert.com
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
