Inbound Routes

The Inbound Routes feature allows service providers to create routing rules based on the dialed (DID) number.

Setup

When adding new inbound routes, it is important to consider the following aspects of the Inbound Routes page.

LATA

This is the LATA of the LRN of the called number. This must match the Called LRN LATA field in the SIP Messages page.

SPID

This is the porting-corrected OCN (Operating Company Number) of the called number. This must match the Called LRN SPID field in the SIP Messages page.

Prefix

A route can be matched to a prefix for a dialed number, or the prefix field can be left blank for the route to apply to any calling number. For Inbound Routes, the prefix refers to the dialed number regardless of whether the number has been ported.

Route Destinations

Routes are created by configuring groups of destinations. A destination must be either an IP address or a hostname followed by an optional port and optional tags. A destination may also refer to a specific trunk ID to route through a specific trunk group. Users can configure destinations based on priority in case of failover. Up to 5 levels of priority are available for configuration: primary, secondary, tertiary, quaternary and quinary.

Within each destination priority level, multiple possible destinations can be listed separated by a comma to evenly distribute traffic.

Destinations per Route

The Destinations per Route number can be configured to control the route failover order. The Destinations per Route number tells ClearIP how many routes from each route destination priority level to return in the Contact header.

If the Destinations per Route is 1, ClearIP returns one destination from the Primary Route Destinations, one destination from the Secondary Route Destinations, one destination from the Tertiary Route Destinations, one destination from the Quaternary Route Destinations and one destination from the Quinary Route Destinations. ClearIP returns 5 routes in the Contact header in the order described. The destination is selected randomly from the available route destinations in each destination priority level.

If the Destinations per Route is 2, then ClearIP returns two destinations from the Primary Route Destinations, two destinations from the Secondary Route Destinations, two destinations from the Tertiary Route Destinations, two destinations from the Quaternary Route Destinations and two destinations from the Quinary Route Destinations. ClearIP returns 10 routes in the Contact header in the order described.

If the Destinations per Route value is equal to or greater than the number of destinations in any particular destination priority level, then all listed destinations for that destination priority level are returned in the Contact header.

Examples

Route inbound calls to specific switch

If ClearIP is integrated to receive inbound calls from an SBC (or proxy) and the SBC must send the call to one of many switches, ClearIP can be used to return a SIP 302 to direct the SBC to route certain inbound calls to a specific switch.

For example, one switch with IP address 1.1.1.1 provides service for 3 phone numbers, and another switch with IP address 2.2.2.2 provides service for 3 other phone numbers. An Inbound Route is created for each individual phone number to define the correct switch to which the SBC should route the call.

These routes are not restricted to the Inbound Service Provider that typically defines calls received from external carriers. The above example is intended to apply to both 1) calls that originate on a switch within the network and terminate on a different switch in the network without being sent to an external carrier and 2) calls that are received from trunks within origination carriers.

How ClearIP Processes Calls in Inbound Routing

Exact Order of Priority of Inbound Routing Rules

As ClearIP processes calls, it will look for an Inbound Route. If only one route matches, it will use that one. If there are multiple routing rules that match, it will use the one with the longest prefix match.

On the Inbound Routes page, there are several columns to the right of the Comment column. The columns to the right define the inbound route’s limiters. When a routing rule is chosen by ClearIP for a particular call, only one of those limiters will apply. The priority of the limiters is as follows, from highest priority to lowest:

1. Calling Number
2. Calling Country
3. User
4. Group
5. Service Provider
6. SBC

There are also several columns to the left of the Comment column. These can be thought of as filters. The LATA, SPID, and Prefix filters will be used to select the rule. Instead of looking at one of these, ClearIP will use all three filters in different combinations, with the longest prefix available taking priority. The priority of the filter combinations is as follows, from highest priority to lowest:

1. LATA, SPID, and Prefix
2. SPID and Prefix
3. LATA and Prefix
4. Prefix

The highest priority limiter and the longest, most specific set of filters will be used to find the highest priority Inbound Route. This is illustrated in the below table: