User requires a feature to populate mobile numbers into tasks and events from related leads or contacts.
From this, they will be able to see the mobile numbers which are more relevant when scheduling appointments with their leads and contacts in Salesforce.
This is also useful when other invitees of the event needs to view the mobile numbers without having to navigate to the related lead or contact records.
In Salesforce, the only data that is brought over from leads or contacts is the phone number. Standard formula and workflow are not the solution to this as they can not work with the Whoid and Whatid in Activity.
To populate mobile number from leads/contacts to tasks/events.