Intraoffice alternate connection arrangement

An intraoffice connection system in a common controlled automatic switching system, comprising:

• a plurality of subscriber equipment;
• a plurality of line link frames for accommodating said subscriber equipment at each line terminal of said line link frames;
• a plurality of intraoffice trunk equipment;
• a plurality of trunk link frames for accommodating said intraoffice trunk equipment, each of said line link frames being connected with each of said trunk link frames through linking means;
• and
• common control equipment including means for controlling connection between a called-subscriber and first idle intraoffice trunk equipment through a first connecting path including a first selected one of said line link frames and a first selected one of said trunk link frames, means for controlling release of said first connecting path together with said idle intraoffice trunk equipment when a second connecting path including a second selected other one of said line link frames and a second selected other one of said trunk link frames for establishing the connection between a calling subscriber and said intraoffice trunk equipment cannot be completed therethrough after connection with said first connecting path, means for controlling connection between said called subscriber and second idle intraoffice trunk equipment through a third trunk link frame other than said first selected trunk link frame in a third connecting path;
• means for controlling connection of said second intraoffice trunk equipment with the calling subscriber through a fourth selected one line link frame and a fourth trunk link frame in a fourth connecting path after the completion of connecting said third connecting path;
• and
• said third and fourth line link frames being independent of said first and second line link frames and said third and fourth trunk link frames being independent of said first and second trunk link frames.