User`s manual
MP-1xx H.323
MP-1xx H.323 User’s Manual 74 Document #: LTRT-65104
5.8.4.2 Tel to IP Routing Table
The Tel to IP Routing Table is used to route incoming Tel calls to IP addresses. This routing table
associates a called / calling telephone number’s prefixes with a destination IP address or with an
FQDN (Fully Qualified Domain Name). When a call is routed through the VoIP gateway
(Gatekeeper isn’t used), the called and calling numbers are compared to the list of prefixes on the
IP Routing Table (up to 50 prefixes can be configured); Calls that match these prefixes are sent
to the corresponding IP address. If the number dialed does not match these prefixes, the call is
not made.
When using a Gatekeeper, you do not need to configure the Tel to IP Routing Table. However, if
you want to use fallback routing when communication with Gatekeepers is lost, or to use the
‘Filter Calls to IP’ and ‘IP Security’ features or to assign IP profiles, you need to configure the IP
Routing Table.
Note that for the Tel to IP Routing table to take precedence over a Gatekeeper for routing calls,
set the parameter ‘PreferRouteTable’ to 1. The gateway checks the 'Destination IP Address' field
in the 'Tel to IP Routing' table for a match with the outgoing call. Only if a match is not found, a
Gatekeeper is used.
Possible uses for Tel to IP Routing can be as follows:
• Can fallback to internal routing table if there is no communication with the Gatekeepers.
• Call Restriction – (when Gatekeeper isn’t used), reject all outgoing TelIP calls that are
associated with the destination IP address: 0.0.0.0.
• IP Security – When the IP Security feature is enabled (SecureCallFromIP = 1), the VoIP
gateway accepts only those IPTel calls with a source IP address identical to one of the IP
addresses entered in the Tel to IP Routing Table.
• Filter Calls to IP – When a Gatekeeper is used, the gateway checks the TelIP routing table
before a telephone number is routed to the Gatekeeper. If the number is not allowed (number
isn’t listed or a Call Restriction routing rule was applied), the call is released.
• Assign Profiles to destination address (also when a Gatekeeper is used).
• Alternative Routing – (When Gatekeeper isn’t used) an alternative IP destination for
telephone number prefixes is available. To associate an alternative IP address to called
telephone number prefix, assign it with an additional entry (with a different IP address), or
use an FQDN that resolves to two IP addresses. Call is sent to the alternative destination
when one of the following occurs:
No ping to the initial destination is available, or when poor QoS (delay or packet loss,
calculated according to previous calls) is detected, or when a DNS host name is not
resolved. For detailed information on Alternative Routing, refer to Section 8.4 on page
154.
When a release reason that is defined in the ‘Reasons for Alternative Tel to IP Routing’
table is received. For detailed information on the ‘Reasons for Alternative Routing
Tables’ refer to Section 5.8.4.5 on page 80.
Tip: Tel to IP routing can be performed either before or after applying the number
manipulation rules. To control when number manipulation is done, set the
‘Tel to IP Routing Mode’ parameter (described in Table 5-12).
To configure the Tel to IP Routing table, take these 6 steps:
1. Open the ‘Tel to IP Routing’ screen (Protocol Management menu > Routing Tables
submenu > Tel to IP Routing option); the ‘Tel to IP Routing’ screen is displayed (shown in
Figure
5-12).