Loss of phone numbers with CardDav

Note on synchronizing phone numbers on Android smartphones

When you add phone numbers to your address book on an Android smartphone, you must define one default number per contact before the numbers can be synchronized. This default number remains assigned to the contact.

However, if you add additional phone numbers to the same contact on your smartphone, these are initially stored locally on the device but are not necessarily synchronized with our servers. If you then add one or more phone numbers for the same contact in mailbox via the web interface, the additional phone numbers on your smartphone may be overwritten during the next synchronization. The reason is that the record modified via the web interface is considered the most recent version.

Caution: In this case, the phone numbers you previously added on your smartphone will be lost.

We have reported this issue to our software vendor and are waiting for a fix. Unfortunately, we do not yet have a release date for a patch that will resolve this problem. We also find this behavior very inconvenient and are pressing for a timely solution. The cause lies in different implementations of standards by various manufacturers – in this case, regarding how many phone numbers a CardDAV entry may contain.