ZyXEL Communications IP PBX X6004 - Manual (Page 50)

Chapter 2 How It Works
X6004 User’s Guide
50
• Outbound Line Group - This is a set of connections or lines going to the
outside world.
• SIP Trunk - This is a connection to your ITSP (Internet Telephony Service
Provider).
• ISDN BRI/PRI Trunk - This is a connection to your ISDN Service Provider.
• Trusted Peer - This is a connection to another IP PBX or SIP server. The
trusted peer device must also specify your X6004 as a trusted peer.
• FXO (Foreign Exchange Office) Trunk - This type of outbound line group
consists of telephone cables connected to ports on an FXO interface card on
the X6004. The telephone cables lead to the PSTN (Public Switched Telephone
Network), or in other words your traditional (non-VoIP) telephone company.
FXO ports always point in the direction of the telephone services.
The figure below shows the relationship between FXS and FXO ports.
Figure 5 FXS and FXO Ports
• LCR (Least Cost Routing) - This is a rule which specifies which outbound line
group is used when making an outbound call. It consists of a dialing condition,
for example dial 0 to make a call via a specific FXO trunk or dial 1 for calls via a
SIP trunk. LCRs also set priority to which outbound line group should be tried
first, second, third and so on when making outbound calls with the same dialing
condition.
• Auto-Attendant - This is a feature which routes incoming calls to their proper
extension. An auto-attendant is assigned to each outbound line group and it
services incoming calls on those lines. If your organization has two outbound
line groups, each with a specific telephone number for incoming calls, then you
FXO
FXO FXS
FXS
PSTN