For the purposes of this guide, the following conventions are used:

The DNS domain name is example.org.

All the applications run on a server called server1.example.org. In practice, you could run each service on a different server and you may duplicate services across multiple servers for N+1 redundancy.

The ICE/STUN process requires two public IPv4 addresses, either on the same interface or on different interfaces. In the examples, the server has two IPv4 addresses on the same interface/subnet, they are 198.51.100.19 and 198.51.100.20. These IP addresses come from the RFC 5737 documentation subnets.

For IPv6, RFC 3849 reserves the address prefix 2001:DB8::/32 for documentation. In the examples, server1.example.org uses the address 2001:DB8:1000:2000::19/64.

The users have existing email addresses such as first.last@example.org and will use the same addresses for both SIP and XMPP.

The internal phone numbers are four digit extensions, such as 8001, 8002 and 8003.