> ## Documentation Index > Fetch the complete documentation index at: https://docs.retellai.com/llms.txt > Use this file to discover all available pages before exploring further. # Dynamics 365 contact sync > Sync Microsoft Dynamics 365 Contacts with Retell AI: field mappings, post-call analysis write-back, and calls logged as Phone Call activities. Contact sync imports your Dynamics Contacts into Retell, writes [post-call analysis](/features/post-call-analysis-overview) results back to their fields, and logs each call as a completed Phone Call activity on the Contact's timeline. This page covers the Dynamics-specific behavior; [CRM integrations](/integrations/crm-overview) explains the four data flows all CRM providers share. Contact sync requires a [connected Dynamics 365 environment](/integrations/microsoft-dynamics). Integration tools work without it — see [Dynamics 365 agent functions](/integrations/microsoft-dynamics-functions). ## Required privileges Sync runs as the [signed-in account](/integrations/microsoft-dynamics#prerequisites), whose security role needs: * **Read** on Contact, including every field you import. * **Write** on Contact for outbound sync. * **Create** and **Write** on Phone Call and Task for activity logging, since Retell creates each activity and then closes it as completed. Attaching them to the Contact also needs **Append** on the activity and **Append To** on Contact. A missing privilege doesn't flag the connection; that field or feature silently stops syncing. ## Set up contact sync After the connection test passes, click **Set up contact sync** to open the field mapping dialog, then map the Dynamics fields you want to import and the Retell fields you want to write back. For a connection made earlier, the same dialog opens from the **Connected** tab: open the connection's settings and click **Set up contact sync**. Retell pre-fills one mapping in each direction: Dynamics `telephone1` (Business Phone) to Retell `phone_number`. Phone number is how contacts are matched between the two systems, so it stays mapped and can't be removed. If your phone numbers live in a different field, such as `mobilephone`, change the external field on both tabs. See [CRM data mappings](/integrations/crm-mappings) for how to map the rest, create custom fields, and choose update modes. To log conversations to Dynamics, turn on **Log activities automatically** on the **Sync to Microsoft Dynamics 365** tab. ## Verify it worked * Open **Contacts**. After the first sync, Dynamics Contacts appear with correctly formatted phone numbers and your mapped fields populated. * The first sync is a full scan of every contact that has the mapped phone field, so a large environment takes a while. After that, Retell polls every 5 minutes (as of August 2026) and imports only contacts modified since the last run. Contacts with no value in the mapped phone field are excluded from the sync entirely, as are contacts whose number can't be parsed into a valid E.164 number. ## How are conversations logged in Dynamics 365? A call becomes a **Phone Call** activity marked completed, with the direction, the duration rounded up to whole minutes, and a description carrying the call ID, the from and to numbers, the disconnection reason, and the summary. A chat becomes a completed **Task**. Both attach to the Contact Retell matched by phone number. ## Troubleshooting Activity logging needs **Log activities automatically** enabled on the **Sync to Microsoft Dynamics 365** tab, a Retell contact that was imported from this connection, and a security role that can create and complete Phone Call and Task activities. A call from a number that doesn't match a synced contact is never logged. ## FAQ By default it only updates Contacts that already exist in Dynamics, and it never deletes them. Turn on **Create new contacts in CRM** on the **Sync to Microsoft Dynamics 365** tab to have Retell create a Contact after a conversation when the matched contact isn't linked to one yet. Your agent can also create Contacts through the **Create Contact** [tool](/integrations/microsoft-dynamics-functions), but that's an explicit tool call, not sync. ## Next steps Map Dynamics fields to Retell contacts, choose update modes, and control what syncs back. Accumulate what your agents learn across conversations into the contact record. Reference synced contact fields from your agent's prompt. Look up callers, update Contacts, and create Tasks and Notes mid-conversation.