The GXW4504 is a E1/T1 Digital VoIP Gateways that allows digital PSTN and ISDN trunks to be integrated with VoIP networks. By connecting the GXW4504 with a VoIP network and a traditional PBX or E1/T1/J1 provider, businesses can drastically increase the amount of PSTN/ISDN trunks integrated with their VoIP network. The GXW4504 provides 4 T1/E1/J1 spans and supports 120 concurrent calls to cater to the VoIP needs of  large sized enterprises.The GXW4500 series supports PRI, SS7 and MFC R2 digital signaling protocols and nearly all major voice codecs including Opus, G.722, G.711, G.729, G.723, iLBC, G.726, GSM-FR, etc. This digital VoIP gateway series includes dual Gigabit network ports with a configurable integrated NAT router, two USB 3.0 ports, and one SD card interface. By adding echo cancellation, jitter buffer, T.38 fax support, TLS and SRTP security encryption as well as automated provisioning by HTTP/TFTP with XML config files, the GXW4500 series is able to cater to the VoIP needs of large and medium enterprises.