put someone on to someone—
1. put smb. in touch with a person, especially by telephone:
- John insisted on being put on to the man in charge.
2. inform of a person’s whereabouts (so that he can be caught):
- Sooner or later he will be spotted in the street, and the police will be put on to him.
put someone through to someone — = put someone on to someone 1:
- He tells me that he can’t help me but he will put me through to someone who can.