SIP to E1 Converter
Without a doubt, it was one of the top 10 projects that I most enjoyed working on. A robust and versatile SIP to R2/ISDN protocol voice converter that serves major telecom operators with NGN networks.
NGN telephony operators that have IP-based voice networks need some equipment at the client end to convert the SIP signaling to the voice interface, usually E1 R2/ISDN.
This demand arose while I was working at a large telecom operator, which started its ngn voice network and from the beginning needed a compact, stable and affordable solution that made it feasible and simple to deliver E1 circuits to the end customer.
Based on Aligera's E1 TDMoE voice gateway, with hardware and engineering design developed by them, I suggested modifying the software design of this gateway to pilot a SIP-E1 gateway. This is because, traditionally, the TDMoE E1 Gateway needed a PBX with a TDMoE interface connected to it to work, being in a way passive equipment since the implementation of the R2, IDSN, QSIG protocols, etc., was performed by the PBX.
We concluded that it was entirely feasible to insert a modified and more compact version of Asterisk into the TDMoE gateway firmware, turning it into a true SIP-E1 Gateway. As at the time there was a limitation of the gateway's processing capacity, we decided which resources should be included in Asterisk for it to work properly.
The result was the creation of the AG521 voice gateway, an equipment with Asterisk embedded, extremely compact, stable and fast, which connects to the E1 port on the PABX Central through MFC/R2 or ISDN protocols and to the ethernet port on the lan or wan network, thus connecting to the sip server.