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Delay between call extensions over the same cisco wireless network


Can someone help me?

I have three escenarios:

************************The first escenario  I have this



***********************The second escenario I have this




**********************The third escenario I have this




All the escenarios have diffrent versión of IOs and different configuratión one off them have the configuratión for a cisco 7921, another only have basic configuration. The three escenarios have multicast on it.

I have a SSID for a voice and I Have this for voice

Phone Motorola EWP 3200

support 802.11a/b/g/n

 Avaya IP Softphone v1.0.0.58


I have the same Issue for all the escenarios that i Have and the issue are when I call another phone in the same WLAN I have a big delay over a voice, it can be at least 2 second  

Any one know if this issue is coused by the WLAN?

Any ideas?




Rasika Nayanajith
VIP Mentor

This could be any thing.

Scenarios you have described are completely different (Autonomous, CUWN, FlexConnet) deployment options & software versions may be completely different.

Focus on one (preferred option 2) & try to narrow down the issue. What is the AireOS version of your 2125 ? (I hope it is, if not get it to that version first).

Then make sure your WLC configuration is align with the recommended configuration for VoWLAN. Below documents may help you



Then connect your two phones onto same 1242 (in 5GHz band) & test.



*** Pls rate all useful responses ***



I have many version of wlc from to 7.4 and I have the same Issue in all version.

In the third escenario my phone are in 5Ghz band and clean air enable and I have the same delay that the phone in 2.4Ghz band.

The data rates in 5Ghz are 1-9 disable, 12 Mandatory, 18-36 supported, 48-54 disabbled

I all ready follow the best practices for a cisco phone 79xx and de best practices for a spectralink phones and  the problem remains






If you can find another 7921, then test it between two 7921. Get a packet capture & see where is the delay occurs. It is good if you can test this with 7925 with latest firmware on it.

Post your "show wlan <wlan-id>" to see how you configure the SSID




*** Pls rate all useful responses ****

I don´t have 7921 for my voice solution, I have a Phone Motorola EWP 3200 working with  Avaya IP Softphone v1.0.0.58 and all the telephony are Avaya.

I  did the test with 3 different telephones in each escenario

And we have the same problem

Leo Laohoo
VIP Community Legend

There are three significant segments in a wireless voice deployment: 


1.  Wireless segment; 

2.  LAN/WAN segment; and

3.  Call Server segment (including how you configured and set up your 7921G)


So far, you've described (vaguely) your wireless segment.  



  1. I'd like to request if you can post or attach a network diagram of where your call server is (in relations to your AP).  
  2. What firmware is your 7921 running?  Start testing the soft-phone with your 7921.  Not a lot of us are familiar with other wireless handset.  
  3. Read the Wireless IP Phone 7925G7925G-EX, and 7926G Deployment Guide.
  4. What happens if you ping the 7921G when you are in the middle of a call?  What are the ping times?  NOTE:  I DO NOT want to know the ping times when the 792XG phone is in idle or no calls are made/received.

Hi Leo Laohoo,

I Will describe my wireless segment.

I have 6 warehouse, in those warehouse I have data and voice over wireless and cable. the voice over wireless is in another vlan than de traditional voice

I have 3 SSID for my wireless network. Data, Voice and one for Symbol device

In all my warehouse I have the same solution for voice and is not cisco the solutions is like this network diagram

And I have diferent cisco wireless equipment in all the warehouses, in one or two I have Autonomos  Access Point cisco 1231, in another one or two warehouse I have WLC  AIR-WLC2125-K9 firmware and Access Point AIR-LAP1242G-A-K9 and in the other warehouse I have WLC AIR-CTVM-K9 firmware and access Point AIR-CAP2602I-N-K9.

I´m testing my best escenario with the WLC AIR-CTVM-K9 firmware and access Point AIR-CAP2602I-N-K9 and I have the SSID for voice working in 802.11a/n, the phones have a RSSI -50 and SRN 30 and the other device are in 802.11 g/n

The lower data rates are disabled for 802.11a/g.

I all ready follow the   Wireless IP Phone 7925G, 7925G-EX, and 7926G Deployment Guide in one escenario and in other warehouse with the same devices a do a simple configuratión for voice with out Qos, CAC, etc.

For rules in the company the security for voice are WEP

And I have the same issue in all my warehouse, working in band 2.4 or 5 Ghz  one of them working with the recomendatios of  Wireless IP Phone 7925G7925G-EX, and 7926G Deployment Guide.  and the other with basics configuratión

Leo Laohoo
VIP Community Legend

1.  Upgrade your WLC to either or 

2.  What happens when you ping the phones during a call?  What are the average ping times? 

3.  You haven't described your LAN and WAN segment.  


In the attachement you will see the network diagram and the image of a site survey in the band 5.2 Ghz.

I hope with this you have a more detail for my LAN and WLAN

I will do the test with the ping and I will tell you the result



Leo Laohoo
VIP Community Legend

  1. Post the output to the command "sh wlan <voice VLAN ID number>". 
  2. What happens when you ping the phones during a call?  What are the average ping times? 
  3. What firmware is your 792XG phones running on?


Hi Leo Laohoo,

In the attachment I hope to answer  your questions 1 and 2

In the file I show you the print screen of one of the wlc and in the last part of the document  you can see the print screen for a ping from two  Motorola Phones before, during and after a call between them

3.What firmware is your 792XG phones running on?

--> I don´t have 792XG phones running on, I have   EWP 3200 Motorola Phone with IP Softphone v1.0.0.58

Leo Laohoo
VIP Community Legend

  1. Disable "Client Band Select". 
  2. Disable 802.11n on the phones.  
  3. Try using OPEN authentication and see if your phone roams better.

Hi Leo Laohoo,

Thank you very much for your advice served me well, was detected that the problem is caused by the Nokia phones and not the wireless network.



Leo Laohoo
VIP Community Legend

Thanks for the update. 


Could you provide us more information, like Nokia reference number to the issue and/or what was/were the finding/findings from Nokia?  


The information will be beneficial to those who might stumble upon this thread and experiencing the same (or similar) issue(s).

Hi Leo,

I hope this reply is not too late...

I could never find information with Nokia about this issue, the solution was found by trial and error and the Nokia solution was compared against  Cisco Solution and the Cisco Wireless ip phone not have the issue

The solution with Cisco works fine.


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