Originally Posted by
Row3Acer
You can not take TG from TPE to ICN because TG is a third country between two cities and these flights are for transfer/connection only (not for passengers initiating flights). Keep in mind that you usually need to take flag-carrier in or out the city that you want to visit.
Not true. Whether TG can serve TPE and ICN for passengers without a connection to/from Thailand depends on whether Thailand has the appropriate aviation agreement with Taiwan and Korea. CX also serves this market. Other examples include SQ flights between US and Europe and US and Japan/Korea. You can buy a ticket from the US to these countries without continuing onto SIN.
Some flights are do require an itinerary continuing to a third country such as the UA segment between SYD and MEL.
According to the published schedules, I would say the agreements are in place and passengers starting/ending travel in TPE/ICN (without connecting to/from Thailand) can take this flight. Travel sites are selling this ticket.
If I was the OP, I'll call back and try again.