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How do FXO ports work?

pirinoe1920
Level 1
Level 1

I am trying to understand how FXO ports work.  I have little experience with this so I am trying to learn how it works at our office.  We have a Cisco 2801 with CME 8.1 and CUE 3.2.  The 2801 has a VIC2-4FXO card in it.  It has 3 analog phone lines attached to it and are setup in a hunt group by the carrier. There is an Auto Attendant setup that prompts a caller with various options for redirecting calls.

1. Question:  When a call comes into the Auto Attendant, I assume this ties up a single analog line.  If there is a second call into the main number it also goes to the Auto Attendant and is routed to the number or appropriate voicemail.  Would this tie up a second analog line? 

2. Question: If a phone in the office is used to make an outbound call or a person in the office calling someone outside of the office at the same time as above, then would this tie up the 3rd analog line?

3. Question: If there is another person calling the AA at the same time as the previous 2 questions.  We get a busy signal.  Does this mean that all 3 analog lines are currently busy and no other call can come in or be made out due to the 3 lines being currently used?

When I run the following commands on the

router# sh voice call sum

port 0/0/0 S_Connect FXOLS_Connect

port 0/0/1 S_Connect FXOLS_Connect

port 0/0/2 S_Connect FXOLS_Connect

 

Also when a port is used and the caller hangs up the phone it takes between 30 and120 seconds for the call to release.  Is this normal for analog lines to take time to release in the phone system?

Are all these things normal or if I am having busy calls then do we have something configured improperly?

Thanks for any help

 

1 Accepted Solution

Accepted Solutions

Manish Prasad
Level 5
Level 5

Hi,

As your router has 3 analog lines connected to FXO port , so at a time 3 call maximum you can receive incoming and call outgoing (if you dont have any other lines or trunk).

1. Would this tie up a second analog line?  - Yes

2. then would this tie up the 3rd analog line? - Yes

3. Does this mean that all 3 analog lines are currently busy and no other call can come in or be made out due to the 3 lines being currently used? - Yes

 

Now apply these two commands under voice port and then check the call release time.

timeouts call-disconnect 1
timeouts wait-release 1

 

Rate all helpful post

Thanks

Manish

View solution in original post

3 Replies 3

Manish Prasad
Level 5
Level 5

Hi,

As your router has 3 analog lines connected to FXO port , so at a time 3 call maximum you can receive incoming and call outgoing (if you dont have any other lines or trunk).

1. Would this tie up a second analog line?  - Yes

2. then would this tie up the 3rd analog line? - Yes

3. Does this mean that all 3 analog lines are currently busy and no other call can come in or be made out due to the 3 lines being currently used? - Yes

 

Now apply these two commands under voice port and then check the call release time.

timeouts call-disconnect 1
timeouts wait-release 1

 

Rate all helpful post

Thanks

Manish

Manish, Thanks. I have added this command to all 3 voice ports 0/0/0 to 0/0/2 but I still have a delay of 140 seconds before the line disconnects. The calls route into the AA but when I hang up it still shows FXOLS_Connect for the 140 seconds. Any other ideas?

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