Verification failed for Mobility (UCWA) service. The Service could not be reached

I have recently been asked to help with an issue where only Lync 2013 mobile clients were not able to connect to Lync server 2013 services.

so I thought it could be could to share the outcome of this information with you.

After double checking the reverse proxy configuration and verified that all required web components and services are properly published, I went to fire up Lync connectivity analyzer

The Lync Connectivity  showed the following results :

There seems to be issues connecting to the UCWA service with url ( being the external webservices url)

“verification failed for Mobility (UCWA) service. The service could not be reached from an external network”

Lync connectivity analyzer

UCWA verification error

Then i tried to access the UCWA services url directly from internet explorer “”

and received an “HTTP 503 error” Service unavailable

so it was obvious that there’s a problem with the UCWA services itself,  It is important to note that the same tests where applied while connecting within the corporate network gave the same results.

knowing that the problem is at the UCWA level, and also knowing that the Lync Server was patched with at least Lync server 2013 CU1 october 2013, it was logic to verify the services from IIS

for information UCWA services virtual directory physical paths are stored under

  • “C:\Program Files\Microsoft Lync Server 2013\Web Components\Ucwa\Ext” for the External Web Services website
  • “C:\Program Files\Microsoft Lync Server 2013\Web Components\Ucwa\Int”  for the Internal Web Services website

UCWA should exist as a virtual directory under Lync Server External Website and Lync Server Internal Website respectively

well so far everything seems right so why the services are not responding ?

Usually a web service is dependent of the following :

the web site status under which it is running, and in this case both websites were up and running

The application pool “LyncUCWA”  that is configured to run both UCWA instances, this can be verified by accessing the UCWA binding settings

since the results showed that the correct application pool is configured i had to also verify the application pool status

and as you can see it seems that the application pool itself is in a stopped state! and this verify the HTTP 503 error generated by IIS, i have proceed in turning on the lyncUCWA pool and running Lync connectivity analyser again

this time the results were good and the error has been eliminated.

although the real reason why the application pool was stopped is still unknown but I have been informed that site administrator has uninstalled unwanted IIS features from the server which might affected the application pool status.


  • Always take into consideration that Lync 2013 mobile clients use UCWA services to connect  where Lync 2010 mobile clients use MCX services to connect to lync services.
  • Never change the  default application pool configured to run UCWA services
  • Use Lync connectivity analyzer tool  to have detailed information on the underlying autodiscovery  process and mobility infrastructure requirements.
  • IIS applicaiton pool state doesn’t change after server restart.

Experienced Consultant Team Lead with a demonstrated history of working in the information technology and services industry. Skilled in Azure, Skype for Business, SQL Server, Iaas, Saas, PaaS, ITIL, Microsoft Solutions, and Servers. Strong information technology professional, technology passionate.

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