Assigns a number to a target. The number will automatically be taken from the company's reserved pool if there are reserved numbers, otherwise a number will be auto-assigned from the provided area code. Target includes user, department, office, room, callcenter, callrouter,
staffgroup, channel and coachinggroup.
Added on Novemeber 18, 2020 for API v2.
Rate limit: 6000 per minute.