Snom One plus
Snom ONE plus is a telephone system (PBX), based on SIP protocol, designed as a universal hardware solution, which includes various options for connecting to PSTN: using analog, PRI (E1, T1, J1), BRI ports. When used with the Snom IP-phone it is a reliable and easy to install solution.
Citel PBXgateways are installed at the central PBX location, and EXTenders are deployed at branch offices, call centers, or at home offices over managed IP connections, DSL, cable, or analog circuits