How to dial CO line reservation in the keyphone system

摘要

1. The technical field to which the invention described in the claims belongs;And a method for reserving a trunk line in a key phone system.;2. Technical challenges to be solved by the invention;When selecting a reserved trunk line, the extension subscriber automatically dials the telephone number of the external subscriber who wants to make a call.;3. The point of the solution of the invention;The method for calling a CO line in a key telephone system according to the present invention includes: a CO line reservation step of reserving a CO line in use and storing an external subscriber number for a call; And a dialing process of automatically dialing the number of the telephone number.;4. Important Uses of the Invention;A key telephone system having a CO line reservation function.