If I have an E1 PRI ISDN GSM gateway (VCL-GSM E1 PRI-30), DX 2030 (Digital E1 VoIP router/gateway Quintum and Internet access of 512 upstream and downstream, can I successfully terminate calls without any connection to the PSTN?With your answer being:
The VCL-GSM E1 PRI-30, this appears only to be a GSM to E1 PRI converter. It therefore has no connection to the IP network to route a call as a VoIP call to the Quintum gateway. You need to have the ability to support VoIP calls on both gateways to bypass the PSTN. A GSM to SIP gateway would be a more appropriate fit here.Could you also have an ISDN to SIP gateway -- in addition to a "GSM to SIP" gateway?
GSM phone ← GSM → GSM to ISDN gateway ← E1 PRI→ Quintum gateway ← SIP→ ITSP (SIP trunking)
If the original goal was simply to be able to call from a GSM phone to the SIP network and have a local E1 connection between the gateways, then this will work without going to the PSTN. A cleaner scenario to accomplish this is to use a single GSM to SIP gateway like that from Quescom. This will also minimize delay.
GSM phone← GSM→ GSM to SIP gateway← SIP → Quintum gateway← E1 to PBX or other equipment→ PBX or other equipment
GSM phone ← GSM → GSM to ISDN gateway← E1 PRI→ ISDN to SIP gateway← SIP→ Quintum gateway ← E1 to PBX or other equipment→ PBX or other equipment
This would not be advised as it adds even further to the overall latency.
This was first published in June 2006