System information

System Administration Guide
300 Main Street • East Rochester, NY 14445 • Toll Free 1-866-ALLWORX • 585-421-3850 • www.allworx.com
© 2007 InSciTek Microsystems, Inc. All rights reserved. Allworx is a registered trademark of InSciTek Microsystems.
Revised: March 28, 2007
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14.3.3 Limitations
While connecting the Allworx IP phone to a network behind a NAT firewall generally works well, there are a
few limitations.
Paging Functions May Not Work
While regular calling and intercom calling works fine, paging functions usually do not. More specifically,
sending pages from the remote phone always works, but neither zoned nor overhead pages will typically be
heard at the remote phone.
Solution: Paging is implemented using IP multicasting. If all the routers between the Allworx
server and the
remote phone can be configured to pass multicast packets, then this limitation can be eliminated. Setting up
a VPN between the Allworx
server and the remote phone may be used to enable this functionality. A full
discussion of the general networking details and the configuration of various router brands is beyond the
scope of this document. However, the Allworx
server details necessary to accomplish this.
On the Servers / VOIP Server page of the Allworx
server, there are three parameters used to configure where
the server transmits zoned pages:
Paging Base IP Address
– This is the multicast base IP address used by the system. Each paging zone uses
the base address plus an offset. Zone 0 (the overhead zone), uses an offset of 0, zone 1 uses an offset of 1,
etc. For example, if the base address was set to 239.255.10.0, then zone 2 would use multicast IP address
239.255.10.2.
Paging Port
– This is the UDP port number that the packets are sent to. All zones use the same port number,
but each have their own multicast IP address.
Paging Max Hop Count
– This value controls the time-to-live (TTL) count in the IP header of all paging
UDP/RTP frames. Typically this value is set to 1 so that the packet will not be sent beyond the local subnet.
However, if you have multiple subnets with phones on them, this value will need to be increased.
Remote Phones behind the same Firewall
Setting up a remote phone that requires static port mappings requires the following steps:
1. Go to the Phone Options section of the Phone System / Handsets / View Configuration page for the
Allworx remote IP phone. The RTP Media Port Range parameter is the range of ports to be used by this
phone. Each phone should be in increments of 10, for example, 16384 to 16393.
2. Set the SIP Port to start in the range of 5060. For example, the remote phone could be set to 5061 if
another remote phone was added previously.
3. Select the update button and reboot the phone for the changes to take affect.
4. The following steps will need to be configured from the phone’s CONFIG / Network Settings menu.
ο DHCP – Disabled (Handsets using static port maps should use static IP addresses).
ο Remote Plug ‘n’ Play key – The key can be found on the Server / VoIP web page.
ο Edit Boot Server IP – Enter the public IP address of your company’s firewall.
ο Edit Phone IP – A static IP address, not DHCP IP address, from the remote site.
ο Edit Netmask IP – Network Mask IP address that corresponds to the static IP address of the remote
site.