Grandstream, connecting the world with award-winning SIP unified communications solutions since 2002, today announced the official release of a new Digital VoIP Gateway. The GXW4500 series offers three models that provide 1, 2 or 4 software configurable E1/T1/J1 spans and support 30, 60, or 120 concurrent calls. By connecting the GXW4500 series with a VoIP network and a traditional PBX or E1/T1/J1 lines, businesses can drastically increase the number of PSTN/ISDN trunks integrated with their VoIP network and increase concurrent calls supported.