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New Member

'90s LAB - high ping between dialup and router

Hello All,

Here is a brief overview of what I have and what I am trying to acomplish.

I have a VG248 with 48 FXS ports.

I have a 2851 ISR with 96 DSP channels.

I have a AS5200 with 48 K56 V.90 microcom modems and a Dual T1 card.

I have a PC with a "v.everything" modem.

So far, I have gotten everything talking to each other.

The VG248 registers each FXS port as an ephone (pots dial-peer) on the 2851's CME.  PLEASE DO NOT TELL ME THIS IS NOT SUPPORTED; We are all "experts" here and can look beyond the manual for once, right?  The AS5200 is connected via dial PRI (nfas) with one D channel (so 47 total B channels).  The AS5200 and the VG248 poth register at POTS dial-peers with g711ulaw as codec of choice. I have been unable to get modem passthrough or relay working as these devices are not VOIP dial peers.  The AS5200 is configured with local auth and PPP. The VG248 is configured for passthrough with Echo CANcelation disabled.

The PC with windows XP is able to dial the AS5200 and connect.  The PC will authenticate, and connect to the "internet". Google has never taken this long to load, thanks to loads of CSS on a blank page...

The issue? Latency.  On a GOOD day, a ping to the AS5200 from the PC will take 250ms, maybe 300ms.  This is really bad.  I think I have narrowed it down to the VG248.  If I use two analogue handsets and call between ports, there is a very noticeable delay between mouth and ear.  I know the stream is not leaving the VG248, so I'm thinking this is the source of my latency.

Does anyone here have ANY experience with the VG248 and noticeable delay through this device?

Can I push my luck and ask if anyone has ever gotten a VG248 to register as a voip dialpeer so I can apply modem pass-through on CME?

Hall of Fame Super Gold

'90s LAB - high ping between dialup and router

That is the reason why fax and modem relay have been invented, these signals cannot be transported over VoIP without the effects you have noticed, or they cannot be transported at all in some cases.

Note you are doing modem pass-through already in this case.

New Member

'90s LAB - high ping between dialup and router

Okay, So if the VG248 is a point of latency, does anyone have any experience with the VG224, or any other AS5xxx series routers?

The AS5200 can only connect via T1-CAS or T1-PRI, and the call is already "digital" as I understand it.  What other gear can I find that will offer lower latency between endpoints?

Now if the VG224/48 can register an an ephone to CME, why is this now a POTS dial peer?

Hall of Fame Super Gold

Re: '90s LAB - high ping between dialup and router

I don't think you can reduce latency on a pass-thorough modem call, in any manner.

Analog ports registered as ephone in CME are technically a pots dial-peer, because at the end of the day that is what they are. But instead of configuring dial-peer, you configure dn and ephone.

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