Exchange autodiscovery not working on Trio over Internet ?

Occasional Contributor

Exchange autodiscovery not working on Trio over Internet ?

Hello dears,


I have spent a few hours testing and checking the web for a clear statement if Trio Exchange autodiscover works or not when a Trio is connected over Internet.


Trio version in test (AG build)


When I put the Trio on my customer LAN Exchange autodiscover works fine for either Exchange on-prem or O365 accounts.

Now taking a new Trio out of the box, provisioning it with USB memory stick for firmware upgrade and configuration file upload is fine but Exchange autodiscover is failing when Trio is attached to Internet.

Taking some traces I found that the Trio does not seem to try all expected urls for autodiscovery process but stops after the first url tested.


My understanding would be that the Trio tries the below:




Nevertheless the first url fails and the Trio do no try the following ones. My customer confirmed me that if the Trio would try the 2nd url it would work as per the DNS setup in place.


Did someone test successfully the Exchange autodiscover when Trio is over Internet access ?

Can we get a clear statement from Polycom if it should work or if there is any specific requirements in regards to Trio configuration, DNS setup,...?


My customer intend is to deploy many Trio on non-Enterprise SfB voice remote sites to promote this technology. Autodiscover is a must have as he has a mix of on-prem and online Exchange accounts.






Message 1 of 4
Regular Visitor

Re: Exchange autodiscovery not working on Trio over Internet ?



I'm seeing something very similar, although in my case it happens on both LAN & Internet. Does your top level domain resolve to something on the internet by any chance?, in my case my domain (lets say '') does. If I browse to, I get a redirect to


The 1st autodiscover request to therefore get's a similar responce, in the Trio logs I see the following (with 'presentation set to debug in log settings')...


pgui |2|00|CSoapTransaction redirect url is =


The Trio then tries autodiscover using that URL and gets un surprisingly gets 'Not Found (203)'


This responce seems to make it give up the entire autodiscover process and it goes no further. I belive this is wrong and it should go on to try, as with your example, I know if it did try, this URL would work. Would be interesting to know if you also see this type of rediect happening as well.










Message 2 of 4
Occasional Contributor

Re: Exchange autodiscovery not working on Trio over Internet ?

Hi Mike23


Right I also get redirected to


I got some progress as I opened a ticket with Polycom and they provided me with version 5.5.2 Beta version.

I focused on Trio over Internet access only. The EWS autodiscover was still failing as long as the Trio queried for  but started to work when it tried


At this time the EWS autodiscover works only to discover the Exchange Web Servicer for users on Exchange on-premise but still fails for user on Exchange online.

For the those last  users I think there is probably a need of user certificate or another certificate. I have to work with my customer who is the administrator of the Exchange part to clarify the requirements from their side.


I would suggest that you get contact with Polycom or your reseller to get this 5.5.2 Beta version and run tests and logs to check if it solves your issue. If not open a case, this product is still under development and I think all feedback Polycom can receive will be valuable,



Message 3 of 4
Regular Visitor

Re: Exchange autodiscovery not working on Trio over Internet ?

I managed to get the re-direct removed from the internal LAN and it immediately fixed my issue, can't be removed from the Internet side but I'm not worried about that for now, it does at least prove this is the cause. Obviously Outlook & Skype client not affected by this so it does seem that the Trio needs updating to handle this scenario in the same way.

Message 4 of 4