1)A single module with 2 E1; 2)Support SIP, H323, SS7, PRI; 3)Locates on the interface of PSTN and IP network; Detailed:VoIP ... one of them. It contains single module with 2E1, support SIP, H323, SS7, PRI and so on. The dimension of this product ... locates on the interface of PSTN and IP network, providing between SS7(ISDN PRI, CAS, V5.2 ) and SIP protocol transform. as well ...