Telephony and Internet Access

In the Circuit Switched Telephony field I worked with the following systems:

  • STP : they forward signalling messages to other STPs in the network, but often these systems were completely programmable, and could also work as matrix, or SCP
  • SCP: contained a database with the users allowed to call, the services associated and their credit.
  • Switching Matrix : connected incoming calls to particular trunks , or event sent the switched calls over the IP network.

In the IP Telephony field I worked with the following systems

  • VOIP gateways : convert POTS calls to packet switched voice stream. Sometimes these platform used their own propietary codec or signalling , or in other cases they used standard G.729 codec and H.323 signalling.
  • SIGTRAN Application Servers and Gateways: systems exchanging telephony signalling information over the IP protocol. The main components were:
    • Application Server : contain user application (SMS, INAP, CAMEL )
    • Gateways: are meant to ensure the interworking between the SS7 network and the SIGTRAN network.

In the internet access field, here is a list of the systems I could have the hands on

  • Remote Access Servers (RAS): they terminated a number of E1 lines, and gave internet access to modem calls succeeding in authentication
  • Broadband Access Server ( BAS or BRAS) : these systems gave internet access to ppp connection originated from ADSL modems