VoIP over WLAN - Client Roaming Settings

Answered Question
Jun 14th, 2010


what would you suggest, are the best settings in the "Client Roaming Section" of the WLC Configuration for the following requirements:

VoIP over WLAN deployment, 802.11a, WLC 4402, 25 - 30 access points (mainly 1252, a few 1130), 7925G phones.

In the moment the settings are set to default, that means: Min. Rssi = -85; Hysteresis = 3; Scan Tresh. = -72; Trans. Time = 5

Unfortunately we are not completely satisfied with the roaming behavior of our phones, so there is the question,

if the roaming behavior of the phones can be improved. Sometimes it looks like the phone takes too much time to make a roaming decision.


Greeting Frank

I have this problem too.
0 votes
Correct Answer by mlieber about 3 years 2 months ago

Hi Frank,

it seems that we have exactly the same issue.

WLC5508, SW 7.0.98

AP1140 and 1250

Phone 7921 and 7925 and 1.4.1 SW Version

Did you have got any news from Cisco about your TAC case?

Best regards


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lissmac_gmbh Fri, 06/18/2010 - 00:04

Hello Aaron,

thanks for your answer.

The phones are already running on firmware 1.3.4 SR1.

And meanwhile, I think I know the 7925G Deployment Guide by heart.

But sometimes the phone simply makes the wrong roaming decision.

Unfortunately it's not 1 out of hundred, it's one out of 10 decisions that's wrong.

Maybe it would be a suggestive feature in the future if one can set "default roaming routes" for the phone.

Greetings Frank

eshawd777 Fri, 06/18/2010 - 22:10

So your wireless network was properly surveyed for and channel/power settings for aps are configured properly? Do you have your WLAN set up for CCKM and WMM? Do you have qos set up for voice?

lissmac_gmbh Mon, 06/21/2010 - 00:48

Our wireless wireless network has been surveyed twice.

The first time to figure out the positions of the Access Points and because there have been changes in amount of APs

and position of some APs, a second time to figure out the ideal power level and channel settings for the changed environment.

The amount of APs and some positions changed, because sometimes there have been two APs in the same office

with an RSSI, let's say 60-65 and the phone was permanently changing the AP, what impacted the quality of the phone call.

The WMM and QOS settings are set for the WLAN, as described in the 7925G Deployment Guide.

CCKM is not set, because we are using WPA2-PSK.

Isn't CCKM of note only, when using 802.1x authentication?

Greetings Frank

Aaron Leonard Mon, 06/21/2010 - 19:54

Frank, what version of code are you running on the WLCs/APs?  If thru,then do please note that the APs are susceptible to:

CSCta29484: Radio stops beaconing for 10-second period (fixed in

CSCte89891 Radio may stop transmitting beacons periodically (affects too)

If the phone doesn't receive beacons for one second, it'll roam to another AP.


Aaron Leonard Tue, 06/22/2010 - 08:04 is not susceptible to those known beaconing problems.

I would recommend opening a TAC case, and being prepared to collect multichannel, NTP-sychronized wireless packet traces, coordinated with phone traces, WLC/AP debugs, and wired packet traces.


Dominic Stalder Thu, 07/22/2010 - 00:49

Hi Frank

have you been able to solve your problems. We have the same issues with 7921 (1.3.4SR1) and, but we are not able to solve the problems.



lissmac_gmbh Thu, 07/29/2010 - 00:49

Hello Dominic,

at the moment we are redesigning the problematic spots in our network

and this will hopefully help to resolve our problems.

Greetings Frank

Dominic Stalder Thu, 07/29/2010 - 00:54

Hi Frank

thanks for the feedback. Actually we are working with the TAC and hopefully we gonna have a solution today or tomorrow.

As soon as I now more I will post it here.



lissmac_gmbh Wed, 08/04/2010 - 03:56

Hello Dominic,

Did you get your problems solved in the meantime?

Greetings Frank

Dominic Stalder Wed, 08/04/2010 - 07:47

Hi Frank

no not at all, we are working with the TAC since 2 weeks and with the business unit (developers) voice and wireless since 2 days, but actually we do not have a solution.



Dominic Stalder Sun, 08/29/2010 - 07:42

Hi Frank

how are you doing with your VoIP design? We also redesigned some spots, but we still have voice gaps and it is annoying.



lissmac_gmbh Mon, 08/30/2010 - 00:47

Hello Dominic

In the meantime, we decided to request for help at another distributor.

They sent their wifi specialist and after one day of testing he was sure,

that this isn't a problem of a wrong configuration or missing coverage or something else,

but it's a failure of one of the components in the wifi network.

Therefore he opened a cisco TAC case and meanwhile cisco is analyzing several debug logs and protocols.

According to the statement of the wifi specialist, cisco should be able to find the failure this week.

We will see......

Greetings Frank

Dominic Stalder Mon, 08/30/2010 - 01:15

Hi Frank

thanks for your feedback, exactly the same process as we are running through.

We arranged a site survey with another wireless specialist (third opinion) and the specialist is also sure, that this can not be a design (configuration or coverage) problem. You can stand next to an access point but the phone will not roam to it in the first 20 - 30 seconds, only after this time the phone can see the access point and roams to it.

It would be nice, if you send me the feedback of Cisco, maybe this would help to force our case. Do you have a case opened at Cisco?

Best regards


lissmac_gmbh Mon, 08/30/2010 - 02:53

Hello Dominic,

if you wish, you can contact me directly by email (f.wagner AT lissmac.com),

i'll send you my contact information and we could exchange information via phone.

Greetings Frank

Dominic Stalder Mon, 08/30/2010 - 12:03

Hi Frank

thanks a lot for your contact information. I will send you a mail or will call you as soon as possible. We got a great message today, there are two Cisco engineers (business unit) comming onsite this week and I hope we are going to solve our problems!

As soon as I know more, I will contact you. But as a hint, if I forget it (this happens a lot at the moment ;-)) just reply to this post and I will contact you.



Aaron Leonard Fri, 09/14/2012 - 16:49

Just following up on this old thread in case anyone stumbles across it ...

The scanning/roaming algorithms in the 792x phones are greatly enhanced in the 1.4.2 (and above) firmware.  Anyone encountering problems such as are described in this thread should be sure that they are running current firmware.


lissmac_gmbh Tue, 09/07/2010 - 23:48

Hello Dominic,

How was the meeting with the Cisco engineers?

Did it help analyzing or even solving your problems?

Greetings Frank

Dominic Stalder Wed, 09/08/2010 - 00:05

Hi Frank

it was very interesting and we saw, that even these experts had to acknowledge, that this building is not easy to cover by wireless. They said that the building is like a bunker and we also found out, that the elevator is interfering the 802.11a band massively.

We found these key points:

- we have RF coverage problem at some spots, but even Cisco had to say, that it is not helpful to install more access points on specific locations --> they are talking with their advanced services to find a solution for that

- on other spots we will install additional access points to improve the coverage

- the wireless expert found two bugs on the phone load, they phone unit is working on it

We should get some answers until Friday.

I will update this post.



Dominic Stalder Thu, 09/16/2010 - 02:29

Hi Frank

actually we god a recommendation for improving the RF situation with external antennas. We ordered the hardware and after that, we will do some onsite tests to see, if it gets better.

On the other side Cisco is working on theses bugs:

CSCtg74904 11n APs stop transmitting and receiving with spike in noise/interference

CSCti74211 CCKM timestamp validation fails on roaming after coverage problem

CSCti74400 7925 reaching max retries causes long connection drop

We are waiting for the firmware they will hopefully provide for us. This are all the news I have at the moment, sorry for not providing any more information.



lissmac_gmbh Thu, 09/16/2010 - 03:45

Hello Dominic,

oh no, that are good news for me.

Because in this moment, I've here an SE  who is making another (the third) one) site survey for Cisco for our TAC case.

And now I've got 3 Bug IDs I can give him.

Maybe we are running into the same problems as you.

By the way, you are also using firmare 7.0.98 on your controller, aren't you. Which kind of controller do you have?

What kind of access point do you have? Are you phoning over 2,4 or 5 GHz?

And have you tested with 7921 phones or 7925 phones?


Greetings Frank

Dominic Stalder Thu, 09/16/2010 - 05:49

Hi Frank

> By the way, you are also using firmare 7.0.98 on your controller, aren't you.

Yes we are using 7.0.98 as controller software.

> Which kind of controller do you have?

We have the 5508(-100) controllers.

> What kind of access point do you have?

Actually we are using the 1142N (dual band), but now we plan to test with the 1262 and the external antennas AIR-ANT5160NP-R.

> Are you phoning over 2,4 or 5 GHz?

We are using 2.4 GHz for data / clients and 5 GHz for the ip phones.

> And have you tested with 7921 phones or 7925 phones?

Yes we tested also with 7921 - it was a little better because of the diversity antenna in the 7921, but we also faced the noted bugs.



lissmac_gmbh Thu, 09/16/2010 - 06:23

It's funny.

We've got exactly the same issues here.

The only difference ist, that we are using 1252 here with a 4402-50 controller.

Greetings Frank

Dominic Stalder Thu, 09/16/2010 - 06:48

"funny" are other things ;-)

Hope with the "new" firmware we can resolve the problems.



thall@deltastar.com Fri, 09/24/2010 - 13:08


I feel like we a suffering from identical issues. I have a 5508 w/ 28 AP ranging from 1242s, 1252s, and 1142s using both 7925s and 7921s for phones. Roaming is atrocious. We just updated our 7925s to R2 of the latest firmware w/ no success in resolving the issue. We too are working on getting TAC and our SE involved to help out. The worst part is that our sister plant in San Carlos Ca across the country for us, not to mention the amount of rogue wifi networks plaguing us. 2 trips out to plug coverage holes and to try to resolve the roaming issue have been futile. I'll throw in any input I get from TAC or other useful resources.

Glad its not just us, but it still sucks for everyone equally.



lissmac_gmbh Mon, 09/27/2010 - 00:19

Hello Dominic,

any news about this annoying issue?

By the way, did you get an information about how much time Cisco will take to solve the Bugs you mentioned

or when they are planning to roll out a new firmware for the phone / WLC, in which these bugs are wiped out?

Greetings Frank

Dominic Stalder Tue, 09/28/2010 - 00:00

Hi Frank

actually we are waiting for the cabling guy, we need to place some more access points.

Concerning the new phone load we got bad news. Cisco is now working on phone load 1.4.x and has not planned to release a firmware for a pico cell environment at the moment. Maybe if the new release is out, they will come back to these bugs.



lissmac_gmbh Tue, 09/28/2010 - 23:48

Hello Dominic,

ok, then I'm very strained, if you can solve your problems completely by (only) adding more access points.

I think, this will help improving the behavior, but it won't help to solve the problems completely.

We already have a cell overlap of 20 % minimum, but the phone simply doesn't work correct all the time.

Well, I think there's a bug, either in firmware of WLC or AP (not in phone, because it's same behavior with 7925 and 7921),

because when you are watching the neighbor list during a call and sometimes the phone doesn't see the next access point to roam to,

how should it roam to it?

The bugs you mentioned, are these all bugs from the phone firmware, or also bugs from WLC or access points?

Greetings Frank

Dominic Stalder Wed, 09/29/2010 - 00:04

Hi Frank

you are absolutely right, we also see these "working issues" of the phone and are sure, that only with more coverage, it won't solve our problems. We are trying to force Cisco for a customized phone load, but this will not happen in the next weeks or months, I think.

But I am happy to hear that also other are facing this problem, because we thought that we are alone with these "phenomena".

These bugs where only on the phone side, no bugs on the WLC or LAP side.



lissmac_gmbh Wed, 09/29/2010 - 01:28

Honestly, I don't know if WE have enough weeks or months, to overlook these issues.

My executive board has already instructed my to proove a dismounting of the whole wlan infrastructure.

Hopefully Cisco comes over with an solution, before they loose their patience.

Because the real sufferers are the distributor, who is not able to help for Cisco's failures an spend extra money and time

and the customer who spend a lot of money and time for an infrastructure and product that doesn't work correctly.

Greetings Frank

Dominic Stalder Wed, 09/29/2010 - 01:34

Not only you are facing this problem, we are spending a lot of time and money to extend the wlan coverage and are not sure if we can solve it. Also our customer is not happy at all and want to see improvements, but this is not happening at the moment.

lissmac_gmbh Mon, 10/11/2010 - 23:22

Hello Dominic,

any news concerning this issue?

Did the additional access points help improving the situation?

Greetings Frank

Dominic Stalder Mon, 10/11/2010 - 23:27

Hi Frank

last week the cabling guy moved some access points and this week they are going to install the new, additional ones.

We expect to be ready for testing in 2 weeks, sorry for still not providing any other news. After these tests we decide how to move on.

Did you hear something from your side, Cisco or network specialist?



lissmac_gmbh Tue, 10/12/2010 - 00:45

We are waiting for a meeting proposal for the visit of the Cisco wlan engineer.

Dominic Stalder Thu, 10/28/2010 - 23:29

Hi Frank

my colleague was there yesterday and tested the hole campus. We added 15 access points and on the floors and corridors we have a good coverage now that improved the voice gaps.

On the other hand we still have some gaps in the stairways around the elevator, because the phone does not roam as aggressive as we need it.

What about your problems?



lissmac_gmbh Fri, 10/29/2010 - 06:18

Hello Dominic,

our problems are still there, no improvements.

We don't get a Cisco SE within the next weeks.

And Cisco TAC is requesting debugs, protocols and so on and we are delivering debugs, protocols and so on

and then they are requesting and we are delivering and so on and so on.

It's really annoying......

Greetings Frank

Dominic Stalder Sat, 10/30/2010 - 06:35

Hi Frank

exactly the same experience as we had during the time of the case. It was really annoying but when we had contact to the Vice president of Cisco, suddenly there was a movement and we ware able to get two really good Cisco experts on place.



muranskycotech Tue, 11/02/2010 - 16:34

Not to question any of the Cisco folks you've worked with, but by chance have they had you run the WLC Configuration Analyzer tool on your WLC?


I just ask because I happened to stumble upon this thread as I was dealing with a couple of my own wireless issues, and I know this utility's advice helped me solve most of the ones I was having.

Dominic Stalder Wed, 11/03/2010 - 00:48


yes indeed, Javier - the developer of the WLC Analyzer - was onsite, so we used the analyzer as a troubleshooting helper ;-)



lissmac_gmbh Mon, 11/15/2010 - 01:33

Hello Dominic,

I've just read in the forum, that a new 7.x code called (an Engineering Special build) is available through TAC.

I was wondering if you have already updated your WLC or if your are going to update the next time.

Because according to the release notes (you find them in the "Other Wireless" section of the forum)

they have fixed one of the three bugs (CSCtg74904) you have posted a few weeks ago, after the visit of the cisco engineer.

Greetings Frank

Dominic Stalder Mon, 11/15/2010 - 01:50

Hi Frank

we did an upgrade to, but not yet to I will just write our TAC engineer, thanks a lot for the hint.



lissmac_gmbh Mon, 11/15/2010 - 05:42

Hello Dominic,

has the "202" release already included the described bug?

Have you noticed any improvements concerning your problems with that "202" release?

Greetings Frank

Dominic Stalder Mon, 11/15/2010 - 07:07

Hi Frank

no the .202 version did not include any solution for our debugs, was just a "nice to have" upgrade.



guilhem.perez Wed, 11/17/2010 - 08:25


I'm in the same context like you (WLC 5508 v7.0.98.0, AP 1142N, IP PHONE 7921 v1.3.4SR1) and we meet VoIP over WLAN issue.

Did you try /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tableau Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} build?

Does this buld improve client roaming issue and others issues?

Could you send me this buld please?

Thank you.

Best regards

Guilhem PEREZ


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