3Com VCX v7111 User Manual page 118

Possible uses for Tel to IP Routing can be as follows:
Can fallback to internal routing table if there is no communication with the Proxy servers.
Call Restriction – (when Proxy is not used), reject all outgoing Tel IP 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 IP Tel 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 Proxy is used, the gateway checks the Tel IP routing table
before a telephone number is routed to the Proxy. If the number is not allowed (number
is not listed or a Call Restriction routing rule was applied), the call is released.
Always Use Routing Table – When this feature is enabled (AlwaysUseRouteTable = 1),
even if a Proxy server is used, the SIP URI host name in the sent INVITE message is
obtained from this table. Using this feature users are able to assign a different SIP URI
host name for different called and/or calling numbers.
Assign Profiles to destination address (also when a Proxy is used).
Alternative Routing – (When Proxy is not 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, see
Gateways Alternative Routing (based on Connectivity and
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, see
Alternative routing (using this table) is commonly implemented when there is no response to
an INVITE message (after INVITE retransmissions). The gateway then issues an internal
408 No Response implicit release reason. If this reason is included in the Reasons for
Alternative Routing table, the gateway immediately initiates a call to the redundant
destination using the next matched entry in the Tel to IP Routing table. Note that if a domain
name in this table is resolved to two IP addresses, the timeout for INVITE retransmissions
can be reduced by using the parameter Number of RTX Before Hotswap.
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
118
Reasons for Alternative
Table
3Com
Configuring the
QoS).
Routing.
31).
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VCX V7111 VoIP Gateway User Guide