As a notice if anyone thinks about using long extension =)
IPO can't use more than 7 digits on H.323 base extension, SIP and DECT work with more.
User extension can be up to 15 digits although some restrictions apply.
Extension Range = 2 to 15 digits.
In general all extensions should have the same number of digits. This setting can be left blank for users used just for dial in data connections.
Users for Delta Server, CBC and CCC should only use up to 4 digit extension numbers.
Users associated with IP phones or who may log in as such devices should not be given extension numbers greater than 7 digits.
Centralized users’ extension numbers can be up to 13 digits in length. Although IP Office supports extension numbers up to 15 digits, the 13-digit length is determined by the maximum extension number length allowed for provisioning Centralized users in Communication Manager.
"Trying is the first step to failure..." - Homer