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New Member

VG248- RJ21 Telco-50 pin (Lucent or AMP standard)???

1. Could somebody please tell me what cabling standard the RJ21- Telco interfaces on VG248 adopt [ AMP Style (ELN27T) or Lucent Style (ELN28T) ] ?

2. Do the analogue devices "See" the VG248 as a PABX from a Layer-1 &Layer2 OSI-model perspective? Thus should any Line adaptors (BT6l-->RJ45) I'm using be PSTN- "MAstered With OverVoltage Protection" OR Secondary-NO MAstering/OverVoltage Protection>?

I can' t find the info anywhere on Cisco website!!

The reason I am asking is that, I am proposing a an IP-Telephony solution that will use the VG248 to connect to Analogue phones, Faxes and modems; but the MAJOR ISSUE is that THERE IS NO EXISTING LEGACY Telephony -wire in the building and hence NO LEGACY Voice Patching Frame. The new building is solely CAT-5 structured Cabling.

My proposed solution will employ a BT6L/RJ11 to RJ45 Line Adaptor unit on each client analogue device which will give, the presentation to connect to the Floor-ports. The product I am using to do this passes the analogue signal to the RJ45 PINS 4+5- PAIR1 on the T568B-Wiring standard.

Thus when these appear at the Data Patching Frame, I then need to provide connectivty from the VG248- Telco50 Pin Cable to a 24-port RJ45-2 wire Patch Panel. Now such a Patch-Panel does NOT EXIST! I have tried various UK & USA manufacturers and they can only produce one custome-built ---very expensive!

For them to produce one, they need to know the PIN-OUTs for the Patch-Panel (I stated PINS 4+5 from the Line Adaptor unit) need to be 'punched' to each individual "pair" from the Telco- 25 Pairs Voice channels.

But they also need to know what standard the RJ21 Telco-50 should use, AMP or Lucent..??

I can' t find the info anywhere on Cisco website!!

Any "Wise" help would be MUCH appreciated. There must be MANY environemnts where nO exisitng legacy Voice-Pacth Frame/ telephony wire exist and the customer wants to use Cat-5 cabling for Analogue devices for IP-Telephony co-existence.....


New Member

Re: VG248- RJ21 Telco-50 pin (Lucent or AMP standard)???


The RJ-21 pinout of the VG-248 is documented here:

Regarding your project, I would go with standard rather than custom-made, mostly for maintenance & cost reasons. You could terminate the VG-248 ports on a regular RJ-45 block (but patched on pair 4-5) and cross-connect from there to the MDF using regular Cat5 patch cables -- in my opinion this would better be done by an installer on-site than custom-made. On the terminal side (analog phones), plug the phones into the wall RJ-45 and they will pick up the central pair (RJ-11 and RJ-45 central pairs are aligned). I'm not sure why you would need an adapter there; FXS ports will act as regular PBX (or telecom company) ports from an analog phone's perspective.



Re: VG248- RJ21 Telco-50 pin (Lucent or AMP standard)???

I approached a different way, I had customer purchase a m-2-m rj21, and a rj11 breakout panel, ( no punching down wires....!) I pluged in the cable to HDA, and another into the VG248 then on other end to the breakout panels.

The cable and panel was about $70 bucks!|Adapters+-+50+pin+Telco&pictures=on&cart_id=5539359

New Member

Re: VG248- RJ21 Telco-50 pin (Lucent or AMP standard)???


Try Panduit solution, patch panel + cable not expensive.

It works fine with cisco vg248



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