If analogue ports are needed, we have the following options:
Integrated Digium PCI cards with analogue ports
Linksys PAP2T adapter (Linksys stopped selling this adapter, SPA 112 is the replacement)
Grandstream HT 702/704 FXS-VoIP gateway
The Linksys PAP2T and the Grandstream gateways are analogue telephony adapter (commonly referred to as ATA).
These gateways enabling high-quality feature-rich VoIP (voice over IP) service through your broadband Internet connection. Just plug it into your network and use the two/four standard telephone ports to connect analogue phones or use one of the ports for a fax machine.
The Gigaset PBX T300 / T500 can configure all mentioned adapter using one touch provisioning (PCI-cards are automatically recognized). The PBX will configure the first SIP account in the Linksys automatically.