Wireless Access

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Occasional Contributor II

Re: VOIP roaming over Wlan with an Android phone

It seems that the Apple producats are better roamer. I will try it asap.
JCO
New Contributor

Re: VOIP roaming over Wlan with an Android phone

Hello,

 

I have made some tests on the same installation of about 12 APs with:

  • 1 Samsung Mini S3
  • 1 iPhone 4
  • 1 VoWiFi phone (OpenStage WL3)

Here is the conclusion:

 

I lose a lot of communications with the Android phone at the roamming time. The authentication time is indeed too long. I can observe a better behavior with ClientMatch enabled but I still lose the communication. As you told me earlier, the Android phone stay too long time on the same AP.

 

The iOS phone works better than the Android one but unfortunately I can also observe some cut during the communication. I lose also the communication if I move too fast on the customer site. But the results are globally much better.

 

With the VoWiFi phone, I never lose the communication.

 

Most of our customers would unfortunately use their Android smartphone to make calls. It's a logical behavior. If you have any other ideas that can help the android smartphone to roam, don't hesitate to share them. 

 

Thanks in advance 

Aruba Employee

Re: VOIP roaming over Wlan with an Android phone

I am not familiar with the backend VoIP server and you haven’t mentioned what Apple / Droid apps you tested. You have enabled QoS on the phone apps and you have checked for the correct QoS end-to-end (IAP to switch to VoIP server)?

 

I've tested and seen some android softphones NOT enable QoS or fail to enable the correct VoIP QoS markings which could impact the packet priority settings and handling in the Aruba ALG. Quick packet capture over the air will show this.

 

I found it good practice to minimize the "IP distance" between the WLAN VoIP client and the VoIP server. If you can provide IP addresses directly from the VoIP server subnet as the VoIP client registers when connected to the VoIP WLAN.

 

Since it is a separate WLAN – SSID although not as secure WPA2-AES will provide a faster authentication when roaming. Unfortunately I did notice that WPA2-Enterprise did slow down the Droid CPU in early versions of the OS.

 

When you have reviewed the packet capture you can open the advanced option in the IAP VoIP configuration to enable and set your WMM preferences.

 

Of course all of this may not alleviate the roaming drops as it is the client that determines when to roam.

 

I have used the Bria softphone (CounterPath SIP softphone) on my android with good results for local testing in my lab to my SIP server (I have the Apple version on an iPad as well) A web search may provide other Apple / Android dedicated VoIP apps you can download and test for a limited time (trial) to find the best for your environment and devices that the user base finds acceptable.

 

Good Hunting

Contributor I

Re: VOIP roaming over Wlan with an Android phone

I have deployed VoWiFi in several hospitals, which are challenging environments, and here is what I have found:

 

  • Layer one and two is king.  Is the wireless networks designed and configured for the voice clients?  If not, you are going to have issues.
  • In every location is there a primary (stronger) access point AND secondary (weaker) access point broadcasting the voice SSID.
  • Do you have areas with large numbers of access points visible?  This can commonly "confuse" smartphones and tablets.
  • If the building is multi-level have you allowed for signal propagating from the floor(s) above/below.
  • During the design phase did you test every corridor and room with a wireless client having a voice call?  Did you walk both directions of the corridor? (west to east followed by east to west, for example)
  • Don't have access points in corridors or other large open plan areas.  If you need to do this then select antennas that will limit the signal propagation.  If you allow the signal to propagate across large areas then the wireless clients will become "sticky" and not want to roam.
  • Try to avoid any wireless feature that will delay roaming.  Some EAP types, Client Match, load balancing, etc can all cause issues.
  • Do packet captures to ensure that the upstream and downstream QoS settings are correct and there aren't an excessive amount of retries.  One capture should be beside the wireless client while the next should be beside the access point.

Lastly, have you used Aruba's excellent Aruba Utilities application for Android?  It has an excellent wireless events area which shows when the Android device roamed.  I have walked up and down a large number of corridors with this application running.

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