https://www.gsmgateway.in/dinstar/Digital-VoIP-Gateway/MTG1000.html
MTG1000 Low Density E1/T1 Digital VoIP Gateway
MTG200 series Digital VoIP Gateways with 1/2/4 ports E1/T1 easily migrate your legacy PSTN networks (legacy PBX or E1/T1 service providers)..
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