Moderator: United Airlines
Join Date: Jun 2007
Location: SFO
Programs: UA Plat 1.995MM, Hyatt Discoverist, Marriott Plat/LT Gold, Hilton Silver, IHG Plat
Posts: 66,854
For sponsoring another person with UA SWUs, the SWUs need to be in your UA account. If there are there this can be done online, the matter is finish. If you require a phone agent, then you will need to go to any airport prior to flight time and authorize the sponsorship.
Sounds like you are applying a CO SWU to an UA flight, which will require an agent and the authorization (but the integration desk may be able to handle that).