One problem with LDAP is VoIP phones have no way of writing a new contact to the address book. LDAP is a very powerful protocol, but it seems VoIP phones don’t use it to write an address book entry. If I’m wrong please let me know - I’d be happy to know about it.

We had a customer using snom phones who needed a simpler way for users to add phone numbers right from the phone keyboard, without logging into the PBX and using the web interface. We saw two possibilities for this: the first would be to use the snom XML and program a small application to collect user input and send it back to the PBX; the second would be to use the local phone address book along with the LDAP address book.

The problem with the XML solution is it would be usable only from the snom phones and would obviously require changes in the PBX.

Using the phone address book is a lot easier and is even possible without making any changes in the PBX. We actually already have a "backup mode" for snom phones - we can set anything we want in the button configuration of the phone. By using the "keyevent" mode with the F_ADR_BOOK parameter, we can set the phone to call up the address book when a user presses a specific button.

This seems to be the easiest solution for now. The beauty of it is it can also be used for other functions; the list of available functions on the phones is quite lengthy.

P.S. We have similar modes also for Grandstream, HTek phones and Yealink phones.