Nortel Networks TP-1610 SIP user manual Configuring the Routing Tables, Tel to IP Routing Table

Mediant 2000 SIP User’s Manual 5. Web Management

5.8.4Configuring the Routing Tables

Use this submenu to configure the gateway’s IP Tel and Tel IP routing tables and their associated parameters.

5.8.4.1Tel 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 (Proxy 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 Proxy server, you do not need to configure the Telephone to IP Routing Table. However, if you want to use fallback routing when communication with Proxy is lost, or to use the ‘Filter Calls to IP’ and IP Security features, or to obtain different SIP URI host names (per called number), you need to configure the IP Routing Table.

Note that for the Tel to IP Routing table to take precedence over a Proxy 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 Proxy is used.

Possible uses for Telephone to IP Routing can be as follows:

•Can fallback to internal routing table if there is no communication with the Proxy.

•Call Restriction – (when Proxy isn’t 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 Telephone 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 isn’t 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 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 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 on Alternative Routing, refer to

Section 8.6 on page 146.

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 5.8.4.4 on page 54.

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

Version 4.4 49 July 2005