Originally Posted by
unavaca
YYZ-ZRH-SIN one-way doesn't contain any UA-operated flights, so UA won't sell you the ticket.
Unless you're trying to FD, you'll probably have to call and book it or use an OTA.
The question is about booking an award ticket, not a revenue ticket. UA award tickets can contain zero UA segments.
I also don't think it's totally true that UA will refuse to sell you a ticket online on a flight with no UA-operated segments. A couple of months ago I went to united.com, typed in "from: IST", "to: LHR", and bought a one way ticket on a nonstop TK flight (TK flight number and operator, 016 plated ticket). This was the cheapest possible way to buy this ticket -- every other OTA and TK's own Web site added a tens-of-dollars booking fee.