The invention provides a call connection control method which can use a conventional telephone as-is and performing linking with a low possibility of mistaking telephones, and a call connection control unit for implementing the method. Upon receiving an outgoing call request from an outgoing-call side personal computer (PC), a call connection control unit retrieves an outgoing-call side IP-telephone linked to the PC, and transmits an incoming call request to the IP-telephone. Upon receiving the incoming call request, the IP-telephone rings. When the caller places the IP-telephone that rings in a starting (off-hook) state, the call connection control unit sends a ring back tone to the IP-telephone and transmits an incoming call request to an incoming-call side IP-telephone. Upon receiving the incoming call request, the IP-telephone rings. When the recipient places the IP-telephone that rings in a starting state, the call connection control unit enables a call between the two IP-telephones.