Let Skype for Business Online users communicate with external Skype for Business or Skype contacts

Thumbnail and link to video: Link Online Extetrnal Communications

You can let people add Lync or Skype users outside your organization to their list of Lync contacts. Go to Admin > Lync > Organization > External communications.

Tip    For a customized list of setup tasks, see Guided walkthrough: Set up Lync Online external communications.

Settings for On except for blocked domains:

Turn on external communications and public IM connectivity

Settings for On only for allowed domains:

External communication setting - only allowed domains


  • You may have to wait for up to 72 hours before the settings take effect.

  • Connectivity with instant messaging providers other than Skype is not available.

Set up communication with external Lync users

  1. Verify your Domain Name Server (DNS) settings for external communications.

  2. Sign in to Office 365 and go to Admin > Lync > Organization > External communications.

  3. Under External access, choose On except for blocked domains


Choose On only for allowed domains, and then add the name of the organization you want to communicate with under Blocked or allowed domains.

Keep in mind:

  • The organization you’re communicating with must also allow communication with your domain. If the other organization has Lync Server on premises, refer them to the TechNet article Configuring Federation Support for a Lync Online Customer.

  • When you’re communicating with someone in a federated domain, you can only use Lync features (for example, video conversations or desktop sharing) that are turned on in both organizations.

  • If the external access setting is changed from “On only for allowed domain” to “On except for blocked domain”, the domains that are listed won’t be kept.

Set up communication with Skype users

  1. If you haven’t already done so, verify your DNS settings for external communications.

  2. Click Organization > External communications.

  3. Select the check box under Public IM connectivity, and then click Save.

Available with Skype* users

Not available with Skype* users

  • Presence

  • Person-to-person instant messaging

  • Person-to-person audio calls

  • Find and add Lync contacts in Skype

  • Video conversations

  • IM or audio conversations with three or more people

  • Desktop and program sharing

* Skype users signed in with their Microsoft account (formerly Windows Live ID).

Notify your users

Once you’ve set up external communications and verified that it works, let your users know what features are available. You can also direct them to these help topics:

Verify DNS settings for external communications

  1. Go to the Office 365 admin center and click Domains.

  2. Select your custom domain name, and then click Troubleshooting.

    Verify your custom domain by clicking Troubleshoot on the domains page

  3. If necessary, update your DNS records as appropriate.

Applies To: Lync admin center, Office 365 Admin, Office 365 Small Business Admin, Skype for Business, Skype for Business admin center

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