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FXO Config for UC540 on BT network

Hi there,

We have a UC540 with 4 analogue lines connected in. The problem that we seem to get is when there are already 2 people on the phone, if anyone else rings in, they will get a busy tone rather than an auto attendant. I know this may be a problem due to UC not hanging up the line quick enough. This is my current config for one of the FXO ports.

voice-port 0/1/0

trunk-group ALL_FXO 64

ring number 3

compand-type a-law

cptone GB

timing sup-disconnect 85

connection plar 398

impedance complex3

description **ANALOGUE LINE**

caller-id enable

caller-id alerting line-reversal

caller-id alerting dsp-pre-allocate

There are 4 separate lines which have the same number and it looks as if there is anther PBX in front as we have to press 9 to dial out if I connect an ordinary analogue phone straight to the line. We used to have an Asterisk system in place of the UC which worked fine.

Any ideas or suggestions that I can try?

Many thanks


paolo bevilacqua
Hall of Fame Master

The way is described , "two free lines but third caller gets busy", doesn't point to the UC but the PBX handling the lines.

You can see what the UC sees with "debug vpm signal" and "term mon".

Hi Paolo,

Just stays off-hook for ages and it never used to do this on Asterisk so I think it is down to the UC.

0/1/0           --  fxo-ls      up    up   idle     off-hook y

0/1/1           --  fxo-ls      up    dorm idle     on-hook  y

0/1/2           --  fxo-ls      up    dorm idle     on-hook  y

0/1/3           --  fxo-ls      up    up   idle     off-hook y

I wanted to make sure I did not need to specify signaling type like ground start. Also, would a Cisco 8800 work fine with the UC?

Hello Dima,

The FXO that hangs - which should be solved if you set the proper disconnect tones for the FXO lines which most probably are not the same as the BT settings which you have set under the FXO ports. You should make PCM capture on the FXO port and find which is the disconnect tone.

Please check the link below:



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