Snom does support LDAP directory lookup for ages. It also supports vCard import.
However, it seems that CardDAV  is becoming increasingly common, particularly in small to medium-sized enterprises .
Therefore I propose adding native CardDAV support to Snom phones in order to lookup contacts stored on CardDAV-based servers. Part of the required code should already be available with the existing support of vCard (data storage format) and LDAP (lookup mechanism) and may be (re)used.
 Many groupware solutions targeted at this kind of customers (take ownCloud/NextCloud/*Cloud as an example) support CardDAV instead of LDAP. These groupware solutions become increasingly popular as they facilitate syncing with mobile devices, where the CalDAV and CardDAV protocol family excels. It is only natural that these kind of customers wish to sync their business telephones with the same dataset as they sync their mobile phones with.
Unfortunately we don't have any time frame yet. Our development receives many feature requests and it is always a challenge to prioritize them. If you would like to discuss your business case and request for a higher priority I would suggest to contact your Snom sales representative.
We are looking for a solution to look up contacts in an external directory. We looked at LDAP but for us, that infrastructure is quite complex. XCAP has the problem of 2000 contacts. The best solutions for us is CARDDAV. Is there any time frame when are planning to implement this feature.
Thank you for the suggestion and details. We have an open feature request for this in our system, with ID SCPP-3560. We don't have an estimation for the implementation yet.