Question

여행사를 통해서 방을 예약했습니다 The verb 통하다 often occurs with -아/어서 attached. Resulting 통해(서) generally translates as 'through' in its various meanings.-아/어서 can be used as a sentence ending. In such usage, -아/어서 cannot be shortened by dropping -서. To form the polite speech style ending, -요 should be added.Expressions with -아/어서 may communicate ambiguous messages due to overlapped meanings. For example, sometimes the meaning may be interpreted both as a sequence of two actions and as an action performed by the means of another action. In such cases, the context can be used to clarify the meaning.

Accepted Answer

I reserved a room through my travel agent

Front	여행사를 통해서 방을 예약했습니다
Back	I reserved a room through my travel agent
Notes	The verb 통하다 often occurs with -아/어서 attached. Resulting 통해(서) generally translates as 'through' in its various meanings. -아/어서 can be used as a sentence ending. In such usage, -아/어서 cannot be shortened by dropping -서. To form the polite speech style ending, -요 should be added. Expressions with -아/어서 may communicate ambiguous messages due to overlapped meanings. For example, sometimes the meaning may be interpreted both as a sequence of two actions and as an action performed by the means of another action. In such cases, the context can be used to clarify the meaning.

아/어서 Meanings 여행사를 통해서 방을 예약했습니다 I Reserved