Quick Guide: Sync Outlook 365 Contacts with iPhone

Without setting up an Exchange server, getting contacts in sync between Microsoft 365/Outlook and iCloud is, frankly, more difficult than it should be. In fact, even with an Exchange account it can be problematic.

A prospective customer recently contacted us for help stating:

When I tried creating something that would work like shared folders in exchange I ran into issues such as synchronizing to mobile devices, removing duplicate entries and real time sync.”

Along with:

“I am aware of Microsoft and their tendency to be difficult and push their obsolete standard. “ 

If you’re are looking for effective ways to sync contacts seamlessly, you’re not alone. This guide will help you navigate the complexities and offer a reliable solution.

Historical Methods of Syncing Contacts across platforms and devices

In the past, IT administrators and users have tried various methods to keep contacts synchronized across devices and platforms. These methods are usually inefficient, leading to synchronization issues with mobile devices, duplicates, incompatibility problems, and a lack of real-time updates. Additionally, if you need extra functionality like granular control over user access permissions to shared address books, the following methods can fall short:

Microsoft Exchange and Exchange ActiveSync: A complex and time consuming solution. Users enable the Contacts sync option in the Exchange/Outlook 365 account settings on their iPhone to synchronize.

iCloud for Windows: Installing the iCloud app on Windows, sign in with their Apple ID, and enable syncing for Contacts and Calendars to sync with the Outlook App.

iTunes Sync: Users would connect their iPhone to a computer, open iTunes, go to the device’s Info tab, and enable syncing contacts from Outlook.

Third-Party Sync Tools: Using third-party services like SyncGene to sync iCloud contacts with Outlook, though these tools often have limitations

Manual Export/Import: Contacts are exported from one platform (e.g., Microsoft365) and imported into another (e.g., iCloud), which is time-consuming and error-prone.

Third-Party Software: Various third-party applications attempt to bridge the gap but often lack reliability and require constant monitoring.

Google Contacts sync: Google Contacts can sync with various email clients and mobile devices that are linked to the same Google account.

Why is it so difficult to sync Iphone contacts with Outlook 365?

No Native CardDAV SupportMicrosoft 365 does not natively support CardDAV, the protocol used by iPhone for contact synchronization
Different Sync Mechanisms365 uses Exchange ActiveSync, which can be complex to configure and may not always work seamlessly with iOS.
Compatibility issues between iOS and Outlook/Exchange ActiveSyncThere have been recurring compatibility problems between the native iOS apps (Mail, Contacts, Calendar) and Exchange ActiveSync, which is used to sync Outlook 365 data.
Software updates and changesUpdates to iOS, Outlook, or Exchange server software can sometimes break existing sync configurations, requiring troubleshooting or reconfiguration.

Understanding DAV Protocols for Syncing Contacts

Unfortunately, Microsoft does not natively support CardDAV. CardDAV is an extension to the WebDAV protocol allowing contact data to be synchronized – The data is transferred as vCards behind the scenes. Here’s a brief summary of common DAV protocols:

For a full guide on transferring contacts from CSV to VCF see our CSV to VCF conversion guide here

WebDAVPrimarily used for file synchronization, enabling collaborative editing and file management over the internet.
CalDAVSpecifically designed for calendar synchronization, allowing users to access and manage their calendar events across different devices.
CardDAVFocuses on contact synchronization, ensuring that contact information is consistently updated across all devices and applications.

Sync Outlook 365 contacts with iPhone, iCloud and IOS

Contactzilla is a CardDAV solution with the primary purpose of keeping business contacts in sync across multiple devices. You can share one or many address books and can give granular access to shared users across those address books.

365 Contact Syncing with Contactzilla and CalDavSynchronizer

COntactzilla + Caldav syn text shown with happy faces showing successful syncing.

When using Contactzilla with an open-source plugin called CalDavSynchroniser, it provides a superb contact sharing and synchronization solution for Office 365. No more sync issues with Office 365 and Icloud devices.

1) Get a free trial of Contactzilla – you can signup here. Here you can create multiple address books to share with colleagues across multiple devices.

2) Visit the Caldavsynchronizer downloads page to install the plugin. Scroll down to the “Changelog” section, and select the most recent version available (e.g. 4.4.1). Open the downloaded ZIP file and install the application

Download the installer from Caldav synchronizer website.

4)Open Outlook and on the top navigation bar click on the ‘CalDav Synchronizer’ tab. Then click on Synchronization profiles.

CalDAV Synchronizer tab

5) Click on the plus (“+”) icon to add a new profile. Then select “Generic CalDAV/CardDAV account” and press OK

Add a new profile

6) The following screen will appear. You can now login to your Contactzilla account to access the credentials you need to fill in the ‘New Profile’ page.

Filling in Contactzilla credentials into Outlook plugin

7) Login to your Contactzilla account, click on the Sync tab in your account and then click on Outlook.

The instructions under this tab are tailored to the currently selected address book. If you want to connect more than one address book, follow the same procedure but first switch to the target address book before selecting this help tab.

Configuration details shown in the Contactzilla app to enter into the Caldav Sync plugin.

This table will help with filling in the ‘New Profile’ screen within Outlook for the CalDav Synchronizer plugin.

NameType a meaningful name for this profile e.g. “Contactzilla CardDAV”
Outlook FolderClick on the “…” button and select Contacts
DAV URLThe URL of the Contactzilla address book you wish to sync, as found in the Sync tab in your contactzilla account with the “https://” part, e.g:
UsernameYour Contactzilla username
PasswordYour Contactzilla password
EmailWe recommend “Outlook <–> Server (Two-Way)” to keep contacts synced between the 2 platforms.
Synchronization IntervalChoose how often you would like to sync. Choose “Manual only” if you would like to choose exactly when you sync.

8) Once you have Caldavsync setup your contacts will stay in sync between different installs of Outlook/Microsoft 365 based on how you have the address books setup. You can connect as many different address books as you need and keep these organized separately in Outlook.

Tip: See our guide on maximizing your business relationships to get your business contacts organized.

How can I connect multiple address books to Outlook?

There is no limit in Contactzilla on the number of address books you create. This means you could create one for suppliers, one for customers. It’s entirely up to you.

1) In Outlook, under the Contacts menu, you will find ‘My Contacts’ on the left with a single folder called Contacts. We recommend keeping this folder separate from Contactzilla for storing private, unsynced contacts.

It is best to create a separate folder for each Contactzilla address book you want to connect. You can do this by right clicking on an existing contacts folder and selecting New Folder:

Creating a new address book in Outlook.

2) When you give the New Folder a name make sure it is of type Contacts:

Creating a new folder with type 'Contacts'.

3) Once you have the folder setup you can proceed to associate it with a profile in caldavsynchronizer. To do this, select CalDav Synchronizer in the main menu, click the green + icon to create a new profile. Set the profile up according to the instructions in Contactzilla under the Sync tab (Outlook) and then select the correct folder.

Associat an Outlook folder with a profile in Caldavsynchronizer.

How can I find shared contacts in Outlook when sending an email?

When you want to send an email to a shared contact, just click the To button in outlook where you specify the address. You will be able to select the address book folder from the drop-down menu. This will show all the contacts you have synced.

Locating shared contacts in Outlook

How can I keep contacts in sync between Outlook and my iPhone?

The great thing about Contactzilla is that it doesn’t care what is connecting to it as long as it speaks CardDAV. iPhones, iPads and OSX all natively support CardDAV which means keeping contacts in sync between Outlook and an iOS device such as an iPhone or iPad is really easy.

Once logged in to Contactzilla head to the Sync tab where you will find instructions for connecting an iPhone. Follow these instructions on the iPhone (or iPhones) and the contacts will stay in sync. If you have connected the same address book to Outlook the contact data will stay in sync between Outlook (Office 365) and the iPhone.

How can I keep contacts in sync between Outlook and an iPad?

The process to keep your contacts synchronized with Outlook and an iPad is simple. Connect Outlook to Contactzilla using the steps detailed above and then setup the iPad using the same Contactzilla address book. The instructions for setting up an iPad can be found under the Sync tab once logged in to Contactzilla.

How can I keep contacts in sync between Outlook and Mac OSX (Sanoma)?

The process to keep your contacts in sync with Outlook and Mac OSX is straightforward. Just connect Outlook to Contactzilla using the steps outlined above and then setup Mac OSX using the same Contactzilla address book. The instructions for setting up Mac OSX can be found under the Sync tab once logged in to Contactzilla.

How can I setup read-only address books in Outlook?

One of the great things about Contactzilla is the ability to give granular access to address books. No access, Admin access, Read/Write access or Read-only access. These settings can be changed inside the teams tab.

1) Invite a user to a Contactzilla address book and give them Read only access as shown.

Granting read only access to a team member.

2) Head over to Outlook where you have Caldavsynchronizer installed. You want to setup a one-way profile. It’s possible to use a Contactzilla read-only account with a two-way profile setup. The user won’t be able to add data to Contactzilla because it won’t allow it with a read-only account, however, caldavsynchronizer will throw an error warning you about this and the error will occur repeatedly. To avoid this, setup a one way sync setup in Synchronization mode. Chose ‘Outlook <- Server profile’ in Caldavsynchronizer as shown below.

Setting the Synchornization mode in Outlook.

As long as you installed caldavsynchronizer on a PC with Outlook you will be able to see the same synchronized contacts in the online version of Outlook for the same account.

How can I see shared contacts in Outlook online (in the cloud)?

One limitation is that in Outlook online these address books are called Categories. Whilst they show up along with contacts as synced from the server, you can’t add a contact to a category from the online version and get it to sync. A contact must be added through the installed app for it to be pushed back to the server.


By integrating Contactzilla with Outlook 365 using CalDavSynchronizer, you can eliminate sync issues and gain precise control over team members’ access rights to shared address books. With the two way connection between Contactzilla and Outlook you will no longer need to worry about duplicate entries. This integration ensures that your contact data remains consistent, up-to-date, and efficiently managed across all your devices, improving overall productivity and collaboration within your organization.

Try Contactzilla

Check out our contact management platform for streamlined contact organization and synchronization on all devices.

  1. Smooth contact syncing solutions tailored for businesses.
  2. Organize, manage, and share contacts within your team with ease.
  3. Apply custom tags and fields for improved contact sorting.
  4. Conveniently import contacts from any location.
  5. Affordable pricing with clarity, scaling with your business’s growth.

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