[This is pre-release documentation and subject to change in future releases. This topic's current status is: Milestone-Ready]

Topic Last Modified: 2010-07-19

Aastra 6725ip and Polycom CX600 are new IP phones for Microsoft Communications Server 2010 (not yet released to the public). Unlike Polycom CX700, a user cannot enter their user name and password on the device to sign in. This is because there is no alpha numeric keypad on these new phones. Therefore, the phone uses DHCP options query results during the startup process to identify and connect to Communications Server 2010. A user can then enter their phone number or extension and authentication PIN on the phone, and the phone will be able to connect to Communications Server. This authenticates the user and allows them to sign in.

To enable phones to discover Communications Server and connect, ensure that the following options are set up on the organization’s DHCP servers:

Option Description Note


CS Pool Certificate Provisioning Service URL

*Specify the internal URL in the form https://ocsWebPoolFQDN:443/CertProv/CertProvisioningService.svc


FQDN for the CA Pool Registrar

* Specify the Pool FQDN of the pool that will be the first logon server for the device. Typically this is a Director pool. If you do not deploy a Director pool, then this is the Front End Pool FQDN. The pool FQDN suffix must match the user's SIP URI.



We strongly recommend that you use a VLAN. However, if you decided not to use a VLAN for unified communications, or if you use LLDP-enabled switches in the enterprise to provide VLAN IDs, then don’t set this option.

Note that option 43 is not an independent option. Depending on the Vendor Class Id, it is configured for; the option may have different values. The client identifies the vendor for which it wants the information as option 60 in the DHCP Request.


Time server

Only needs to be configured in an intranet only environment and a PIN authentication scenario to resolve time server address.

* These are general examples. For more information, see Appendix: Configuring DHCP Options on DHCP Servers other than Windows DHCP Server.

For a HQ or central location which is typically serviced by a datacenter, configure DHCP Options mentioned below on the DHCP servers in the datacenter. For branch sites where a Survivable Branch Appliance is deployed, you can configure a DHCP server if it is available in the branch, or alternatively enable Communications Server DHCP. When Communication Server DHCP is enabled, Communications Server itself replies back to the DHCP Options queries for DHCP options 120 and 43. Note that Communications Server DHCP is not a full DHCP server. It does not provide leases, it only provides the options specified above.

Option 120 contains the CS Register Pool FQDN Servers that Communications Server clients can connect to. For example, if example.com is the SIP Server, the value for option 120 would be as follows: 0 7 ‘e’ ‘x’ ‘a’ ‘m’ ‘p’ ‘l’ ‘e’ 3 ‘c’ ‘o’ ‘m’. Note that Communications Server only supports encoding type “0” and “1”.

To allow IP phones to discover the Communications Server, follow these steps to configure the DHCP server
  1. Add DHCPUtil.exe and DHCPConfigScript.bat on a network share that can be accessed from the DHCP server.

  2. On the DHCP server, run the following at the command prompt:

    \\<FileShare>\DHCPUtil.exe -SipServer <Communications Server Pool FQDN > -WebServer <Communications Server Internal Web FQDN> -RunConfigScript.

    The Communications Server Internal Web FQDN is the FQDN of the Web Components that run on the Communications Server Pool. This is typically specified by using Topology Builder as part of pool properties. If you do not use DNS Load Balancing for the pool, then the Communications Server Internal Web FQDN is the same as the Communications Server pool FQDN.

  3. To validate that the DHCP options entries were created and that a client computer can discover Communications Server using this DHCP configuration:

    • Run DHCPUtil.exe -EmulateClient” on the client computer. If it returns success, the entries were created correctly. Currently this can only be run with just one active network adapter.

DHCPConfigScript.bat essentially does the following:

Copy Code
netsh dhcp server add optiondef 120 UCSipServer Binary 0 comment="Sip Server FQDN"
netsh dhcp server set optionvalue 120 Binary <value of option 120>
netsh dhcp server add class MSUCClient "UC Vendor Class Id" "MS-UC-Client" 1
netsh dhcp server add optiondef 1 UCIdentifier Binary 0 Vendor=MSUCClient comment="UC Identifier"
netsh dhcp server set optionvalue 1 Binary vendor=MSUCClient <value of sub-option 1>
netsh dhcp server add optiondef 2 URLScheme Binary 0 Vendor=MSUCClient comment="URL Scheme"
netsh dhcp server set optionvalue 2 Binary vendor=MSUCClient <value of sub-option 2>
netsh dhcp server add optiondef 3 WebServerFqdn Binary 0 Vendor=MSUCClient comment="OCS Internal Web Fqdn"
netsh dhcp server set optionvalue 3 Binary vendor=MSUCClient <value of sub-option 3>
netsh dhcp server add optiondef 4 WebServerPort Binary 0 Vendor=MSUCClient comment=" OCS Internal Web Fqdn Port"
netsh dhcp server set optionvalue 4 Binary vendor=MSUCClient <value of sub-option 4>
netsh dhcp server add optiondef 5 CertProvRelPath Binary 0 Vendor=MSUCClient comment="Cert Prov Relative Path"
netsh dhcp server set optionvalue 5 Binary vendor=MSUCClient <value of sub-option 5>

See Also