1. From System > LDAP > LDAP Directory, choose the Directory URI mapping to the appropriate LDAP attribute. In my case I will use the mail attribute as the directory URI.
3. Check your DN again, you should see the directory URI appears magically.
4. The Directory URI is put into an automatically generated partition called "Directory URI". If you wanna call other DN with Directory URI configured, make sure your CSS has the partition Directory URI.
You can try to make a call now. It only supports on hook dialing for URI dialing, so you press the new call softkey, the press the "A B C" softkey so that you can enter alphanumeric characters.
If you don't want to call the full directory URI, you want to call without the domain name, make sure you change the following in the Enterprise parameter.
One point to note, when you have the URI and name configured on the DN, even you call each other via DN number, the bubble display on phone will still shows URI instead of DN number, even in the Call List it will show URI instead of DN, so when you redial actually you are calling back via URI instead of DN.
Test your call now and good luck!