Installation & Operation Manual 670 Document # LTRT-92224
Mediant 8000
Filter Calls to IP – When a Proxy is used, the gateway checks the Tel to 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
Always Use Routing Table – When this feature is enabled (Always Use Routing
Table = Enable), 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.
Alternative Routing – (When a 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.
The call is sent to the alternative destination when one of the following occurs:
• No ping to the initial destination is available, or when poor Quality of Service
(QoS) (delay or packet loss, calculated according to previous calls) is
detected, or when a DNS host name is not resolved. For detailed
information, see 'Alternative Routing Provisioning Rules' on page 679.
• When a release reason that is defined in the ‘Reasons for Alternative Tel to
IP Routing’ table is received. For detailed information, see 'Reasons for
Alternative Routing' on page 679.
Alternative routing (using this table) is commonly implemented when there is no
response to an INVITE message (after INVITE retransmissions). The Mediant 8000
then issues an internal 408 ‘No Response’ implicit release reason. If this reason is
included in the Alternate Tel to IP table, the Mediant 8000 immediately initiates a call
to the redundant destination using the next matched entry in the Tel to IP Routing
table.
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,Proxy Hot Swap Rtx in SIP
Proxy settings. See the the table, 'SIP Proxy Settings' on page 547 for details.
If the alternative routing destination is the gateway itself, the call can be configured to
be routed back to PSTN. This feature is referred to as ‘PSTN Fallback’, meaning that if
sufficient voice quality is not available over the IP network, the call is routed through
legacy telephony system (PSTN).
Note: Tel to IP routing can be performed either before or after applying the number
Operation rules. Tel to IP routing can be performed either before or after applying
the number Operation rules.
To control when number manipulation is carried out, set the TEL to IP routing
mode parameter SIP Protocol Settings screen.
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