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Community Member

Maximum RJ-11 Distance for ATA-186/88?

I can't find documentation that states what the maximum supported distance for an RJ-11 run is. I'm interested in centralizing the ata devices in the computer room and having the RJ-11 runs go out to the phones (there isn't cat5 where the phones are, and I don't have enough phones to go the VG248 route). Does anyone know how much line these units can drive?

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: Maximum RJ-11 Distance for ATA-186/88?

Each telephone set provides a Ringer Equivalence Number (REN), as defined within FCC Part 68 and RS-470. Some examples of RENs are:

1A

1.5A

0.5B

2L

etc.

The REN is used to ensure that the central office (CO) can provide the correct amount of power required to ring the telephone set. As ringers are added to the circuit without additional power supplied (overload), the voltage will drop to a point at which the telephone ringer(s) will not operate properly.The REN is expressed in units and tenths, then followed by a letter. The letter describes the Frequency Range, Power Range, and Bias (VDC) range of the telephone set. These letter designations are further explained in EIA RS-470.

For the U.S. Public Switched Telephone Network (PSTN), the REN letter must be either 'A' or 'B'.

When the phone is answered, DC current begins to flow in the loop. The Central Office senses the current flow and removes the superimposed Ringing Voltage.

MOST CENTRAL OFFICES IN THE PSTN CAN SUPPLY 4 TO 5 RENs PER LINE.

So the phone you connect to the ATA should have a ren number either labeled on the phone or printed in the technical specifications of the phone.

4 REPLIES
Cisco Employee

Re: Maximum RJ-11 Distance for ATA-186/88?

For a guideline on distances for the ATA (depends on REN) see:

http://www.cisco.com/univercd/cc/td/doc/product/voice/ata/ataadmn/sccp/sccpach5.htm#1034692

Community Member

Re: Maximum RJ-11 Distance for ATA-186/88?

Please excuse my ignorance, what is the REN rating, and how do I determine which category I fall under?

Cisco Employee

Re: Maximum RJ-11 Distance for ATA-186/88?

Each telephone set provides a Ringer Equivalence Number (REN), as defined within FCC Part 68 and RS-470. Some examples of RENs are:

1A

1.5A

0.5B

2L

etc.

The REN is used to ensure that the central office (CO) can provide the correct amount of power required to ring the telephone set. As ringers are added to the circuit without additional power supplied (overload), the voltage will drop to a point at which the telephone ringer(s) will not operate properly.The REN is expressed in units and tenths, then followed by a letter. The letter describes the Frequency Range, Power Range, and Bias (VDC) range of the telephone set. These letter designations are further explained in EIA RS-470.

For the U.S. Public Switched Telephone Network (PSTN), the REN letter must be either 'A' or 'B'.

When the phone is answered, DC current begins to flow in the loop. The Central Office senses the current flow and removes the superimposed Ringing Voltage.

MOST CENTRAL OFFICES IN THE PSTN CAN SUPPLY 4 TO 5 RENs PER LINE.

So the phone you connect to the ATA should have a ren number either labeled on the phone or printed in the technical specifications of the phone.

Community Member

Re: Maximum RJ-11 Distance for ATA-186/88?

Thanks, thats just what I was looking for.

Jeff

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