Specifications: It is an ideal complementary product to any sip based ip pbx. It allows the user to get very cheaply from ip to gsm network and vice versa. Ethernet (rj 45) connection is a significant advantage in most of the cases. Voiceblue offers voip services (internet telephony), advantages of digital gsm gateways, lcr, getting 100% control over all calls aiming to gsm is one of the main advantages, clip routing, sms messages.