Customers currently on the Lync 2013 Enterprise (IM/Presence & Conf) User subscription will be unable to set a PIN for Lync voice conferences as this feature requires a phone number assigned to them, which is not included in this plan.
If a user attempts to set the PIN manually via the Meeting URL they will receive the following error:
"A phone number has not been configured for you. Please contact your support team with this information."
What is a PIN?
A PIN is a Personal Identification Number used to ensure you are the scheduler of the conference and in this instance would mean that a phone number has not been configured for you.
Generate a Pin
This must be reported to the Technical Support team who will escalate if necessary and manually set a PIN for the SIP address; this PIN must be a minimum of five digits and can be specified by the customer if necessary.
After the PIN has been assigned, the customer can then dial-in to the conference meeting and use the PIN to ensure they are given the privileges of "scheduler".