ASCOM i62 Wi Fi phones on 7.6 code 5508 WLC with 3502i AP's Messaging Only error

[Sean Coogle]

I have numerous ASCOM i62 phones on 5508 controllers with a dedicated SSID. All of the setup is to ASCOM specs and this has been working for almost two years with no problems. I am finding it hard to pin point an issue as nothing is easy to recreate and it is very intermittent. All of the phones connect on 5GHz and ASCOM claims it is interference. Prime shows no interference other than blue tooth. If I have 3 phones in the same room and one of the three go to the 'messaging only' error and drops calls while all the others are fine, I find it hard to believe it is interference. Will putting an AP into sniffer mode and sniffing the traffic at a know problematic location for a phone help me with interference logs?

[Leo Laohoo]

Be very afraid about what ASCOM "engineers" tell you.  We had a rollout of ASCOM phones a few years ago (don't ask WHY we chose them).  The very minute they hit the ground, nothing works well.  For an ENTIRE YEAR ASCOM engineers told us to "change this settings" or "change that settings" on the WLC but never on the ASCOM phones or servers.  

It took a "hijacked" Cisco TAC engineer to determine that ASCOM phones were not performing well because the ASCOM phones had a bug when the phones were configured for 802.11n.  Once 802.11n was disabled on the phones, everything started improving.  Cisco TAC had to tell the ASCOM code writers WHERE the faulty code was.  ASCOM firmware were poorly written and didn't follow 802.11n standards and this is what broke.  The minute you turn OFF 802.11n the phones are able to become functional (to a limited degree).

It still wasn't ideal because ASCOM phones dictate that the APs need to have DCA and TPC DISABLED.  So basically, their setup means that we shouldn't have deployed WLC-based system.  

[gerrydubois]

Leo, very interesting comment.   I am testing a VoWiFi device that uses the same radio chipset that the Ascom i62 does, and we see similar results.  We have a deployment on a WLAN that uses Cisco 1131 AP's (802.11bg), and the devices work great.  But on 2602's (11n 5GHz) or 1142's (11n 2.4GHz), we have similar issues of some devices working well, while a nearby device may experience choppy voice quality or network drops.  

What were the details of the problems that you were initially facing with the i62's, and were you every able to fully overcome them?  If so, how?  

Do you have any additional information regarding what the Cisco TAC engineer discovered?

[Leo Laohoo]

Cisco has identified it as Bug ID CSCud65237.

With your 2602, try and disable 802.11n on the phones.  

The issue we had was the i62 had difficulty in roaming.  ASCOM phones were marking some 802.11n packets as 9 and above.  This is not the standard.  Standard dictates the marking to be 7 and below.  So when the WLC saw it, the WLC did the only thing it knows how to do, dropping the unknown packets.

[George Stefanick]

Something else you should know. The i62 has a much lower receive sensitively. See attached. The i75 and Cisco 7925 hear the same ap at the same RSSI. The i62 attached to the same ap hears it almost 10dB lower! -49 -49 -58 ! 

 

[Leo Laohoo]

Thanks for this information, George.  

+5!