Dial plans exist in both Exchange and Lync, but are separate objects and won’t always have a 1:1 ratio. Management can be simplified by always creating a matching dial plan in Exchange for each Lync dial plan, but this is not necessarily required. Drivers for creating distinct Unified Messaging dial plans come down to the following considerations:
• Operator Extension—Each UM dial plan can have only a single operator extension. If users expect to reach different operators by pressing 0 after calling the Subscriber Access number, create a second dial plan.
• Default Language—Each UM dial plan can support multiple languages, but voice-to-text message preview occurs only for the default language.
• Unique Extensions—UM dial plans require each user to have a unique extension. Users in two sites can have the same extension through the use of site prefixes or steering codes, but each site requires its own UM dial plan.