Consider this scenario in Microsoft Skype for Business 2016 (Click-to-Run):
- User A has a SIP URI that starts with a plus sign followed by a few digits, formatted like a TEL URI. For example, sip:+15555555555@contoso.com.
- User A also has a Line URI that matches the number in the SIP URI. For example, tel:+15555555555.
- User B tries to call the Line URI of the first user, and upon connecting places the call on hold.
In this situation, user B hears a ringback tone while the call is on hold.