The phrase is never used in regular conversation, but explicitly implies connecting you to your intended call destination. Used only by telephone operators (typically the reception desk of a company).
In the early days of the telephone, an operator would "patch you through to [person]" as they had to physically control a switchboard in order to connect your call to its intended destination. The phrase you are mentioning is a shorter version of the same, as an operator (the person in charge of receiving all calls in a business or any organization) redirects your call.