Abstract: Even though selecting the outbound call route on IP-PBX System in original form with fixed channel and pattern matching techniques was accurate, it caused high network traffic on the GSM network. The purpose of this research was to resolve this problem by using K-Nearest Neighbor (KNN) technique in database mining together with Unstructured Supplementary Service Data (USSD). The results of this research showed that using the proposed technique with a SIM3000CZ Microcontroller board was able to select the outbound call route correctly according to the name of network operators. It also reduced network traffic between the operators. Moreover, using KNN technique and database mining was able to decrease overhead caused by the procedure of USSD technique in selecting the outbound call route.