Web Proxy Auto Discovery (WPAD)

The Web Proxy Auto-Discovery Protocol (WPAD) feature enables Polycom phones to locate the URL of a Proxy Auto-Configuration (PAC) file you configure. Microsoft recommends using Blue Coat proxy with WPAD.

Polycom VVX business media phones support WPAD beginning UC Software 5.7.0 and later.

WPAD is enabled by default. You can configure WPAD using configuration parameters on your provisioning server, DHCP Option 252, or DNS-A protocol mechanism to discover the PAC file location. When using a provisioning server or DHCP, the phone looks for the file name you specify. If using DNS-A, the phone looks only for the wpad.dat file.

The priority for PAC file searching is as follows, from first to last:
  • Provisioning server. Example: feature.wpad.curl="http://server.domain.com/proxy.pac
  • DHCP Option 252. For instructions, see Creating an Option 252 entry in DHCP on Microsoft TechNet: https://technet.microsoft.com/en-us/library/cc995090.aspx
  • DNS-A. For instructions, see Creating a WPAD entry in DNS on Microsoft TechNet: https://technet.microsoft.com/en-us/library/cc995062.aspx
    Note: If the proxies you configure in the PAC file or configuration file are either invalid or unreachable with a working fallback proxy, the time to register with Skype for Business is delayed and the responsiveness of features that support WPAD degrade.
Polycom phones support Digest and NTLM Authentication mechanisms to authenticate with a proxy server. When you sign in to Skype for Business, the phone uses the Skype credentials to sign into the Web proxy. To manually configure proxy-specific credentials common to all users, use Basic Authentication which is supported only when you configure the following parameters on a provisioning server:
  • feature.wpad.proxy.username
  • feature.wpad.proxy.password

Supported HTTP/HTTPS Web Proxy Services

When the Web proxy server is successfully configured and operational, Polycom phones route the following HTTP/HTTPS Web proxy services to the Web proxy server:

Skype for Business Services

  • Registration Services
  • Address Book Service (ABS)
  • Location Information Server (LIS)
  • Device Update (To ensure reliable software updates, device update is direct in case a proxy is not available.)
  • Server Log Upload
  • Exchange Web Services
  • HTTP/HTTPS Provisioning
  • Core File Upload