Updating SIP Addresses in Skype for Business

When you migrate to Office 365, the preferred configuration is to have user email addresses and UPNs the same. Having a single identity makes it easier for users to understand.

If you are implementing Skype for Business in Office 365, it will take the UPN of the user as the Skype address. Again, keeping a single identity is good.

However, if you have an on-premises implementation of Skype for Business, then the Skype identity is configured in the attribute msRTCSIP-PrimaryUserAddress.  This attribute contains a SIP (session initiation protocol) address that looks like an email address but with “sip:” at the start. For example: “sip:user@contoso.com”.

The SIP addresses defined in your on-premises Skype for Business may or may not match the email addresses of the users. You need to verify whether the addresses match. If the SIP address does not match the email address, it is easy to change.

On the Skype Server run the following PowerShell command:

Set-CsUser -Identity userUPN -SipAddress "sip:emailaddress"

When you update the SIP address for UserA there are two considerations:

• UserA will be signed out of Skype within about 1 minute. After UserA is signed out, they need to sign in again by using their new SIP address.
• Any users with UserA as a contact are not updated immediately. These users need to sign-out and sign-in again for the contact to be updated and properly view presence information. However, this only works if the address book as been updated.

Address book updates are the big gotcha in SIP address updates. By default, Skype for Business clients use a cached address book that only updates once per day. Even if you force address book updates on the server, the new address information is not retrieved until the next day unless you manually delete the cached address book files from the client to force a reload.

To address this problem, you can switch clients to use an online address book. Clients using the online address book query the Skype for Business server each time they search the address book. When using the online address book, changes show up within a few minutes.

Address book look ups are controlled by client policies. By default, there is one policy named Global. You can update this policy to use online address book resolution with the following command:

Set-CsClientPolicy -Identity Global -AddressBookAvailability WebSearchOnly

Alternatively, you can create a new policy and assign that to users incrementally:

New-CsClientPolicy -Identity OnlyWebAB -AddressBookAvailability WebSearchOnly
Grant-CsClientPolicy -Identity UserName -PolicyName OnlyWebAB

The new client policy takes effect the next time the user signs in. To increase the likelihood that users have the new policy, you should configure it and then wait until the next day before making large scale changes.

Some useful links:

• Video showing results of changing SIP address
• Anatomy of a SIP Address Change Part #2
• Forcing Lync Address Book Web Query
• Troubleshooting addressbook issues in Lync 2013/Skype for Business