SCCP VG224 w/OPX lines

Unanswered Question
Dec 17th, 2009

Weird issue here.

We have a VG224 configured with SCCP and we are experiencing an issue with an analog phone not ringing (audible).  The call flow is such that the call will go out the VG224 FXS over an OPX line and ring down an analog phone.   The issue is that the analog phone does not ring so that the end user can hear that they have an incoming call.  The calling party DOES hear ringback and if the called party (analog phone) picks up they will have 2-way audio.  The issue is that there is never any audible ringing on the analog phone side.

VG224 running 12.4(24)T2. Other analog devices on this VG224 work with no issues.  Its only a couple OPX lines that are having this issue.

Any ideas?

I have this problem too.
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asandborgh Thu, 12/17/2009 - 13:47


This sounds like a REN problem - ringer equivalency number.  If you have too many analog phones  (generally in the US more than 5) on the same line they may not ring, or may have ring issues.  Even if you have only one phone on the line, but it is a long distance from the device trying to ring it you can have the same issue.  I have seen this in large plants where it is a long run of copper to the phone (in my case through several buildings).  Additionally if there are intermediate devices you can have issues with this as well.  Please note that even though they don't ring, in most other cases - as you describe- they may work just fine.

Here are the ring related specs from the VG224 data sheet:

Ring Voltage

50Vrms into 5 REN at zero loop length (balanced) if no DC offset

54Vrms into 5 REN at zero loop length (balanced) if no DC offset

Ring Frequency

20, 25, 30, 50 Hz

20, 25, 30, 50 Hz

Ring Waveform

Sine wave if no DC offset

20V and 24V DC offset will be trapezoidal

Sine wave up to 35V DC offset

Ring Load

5REN with no DC offset

2REN with DC offset

5REN with no DC offset

2REN with DC offset

REN Loading

5 REN/port, 12 REN/system (maximum)

5 REN/port, 12 REN/system (maximum)


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