AT&T IP Flexible Reach Customer Portal: Group Administrator Support

About Trunk Call Routing

Overview

In an AT&T IP Flexible Reach enterprise, trunk call routing provides the intelligence that routes calls to one or more group trunk groups according to the scheme an Enterprise Administrator sets (for example, routing calls between two customer service sites). The Enterprise Administrator sets trunk call routing scheme properties that determine how a call is handled. The trunk call routing scheme then routes an incoming call between group trunk groups according to the properties selected.

As an IP Flexible Reach Group Administrator, you can view a group trunk group's associated trunk call routing scheme within the AT&T IP Flexible Reach Customer Portal.

Note: As a Group Administrator, you cannot edit trunk call routing schemes. The ability to view a trunk call routing scheme is permission-based. You may or may not have permission to view trunk call routing schemes within your enterprise, based on how your enterprise was set up. You've been granted one of the following permission levels:

View Only—You can view but not edit trunk call routing schemes.
Hidden—You can't view trunk call routing schemes.

Routing Algorithms

An Enterprise Administrator can specify the order in which calls are sent down the various routes and how to respond when one route is operating at maximum capacity and others aren't.

The rules that Enterprise Administrators apply are called routing algorithms. When setting up trunk call routing schemes, they can choose from these four algorithms:

Linear
Round Robin
% Allocation
Most Idle

Linear

The most basic routing algorithm is the Linear algorithm.

Enterprise Administrators use the Linear algorithm to set the order in which group trunk groups receive traffic. If the first group trunk group isn't available or has reached its capacity for concurrent calls, the traffic is routed to the next group trunk group in the trunk call routing scheme. When that group trunk group reaches capacity, traffic shifts to the next group trunk group, and so on, in the order specified by the Enterprise Administrator.

The first group trunk group in the order is created by default when AT&T sets up your service. The search then follows the order in which the Enterprise Administrator adds group trunk groups to the trunk call routing scheme. To change the search order, the Enterprise Administrator must create a new trunk call routing scheme.

Linear Scenario

An enterprise has two sites and wants to route all Site 1's incoming calls to Site 2 if Site 1 fails. The Enterprise Administrator sets up a Linear scheme for the two sites. A call comes into Site 1, which is unable to handle the call, so it's routed to Site 2.

Round Robin

The Enterprise Administrator uses the Round Robin routing algorithm to spread incoming calls evenly across the group trunk groups.

Like the Linear algorithm, the Round Robin algorithm selects resources in sequence, but the Round Robin algorithm has an added feature: Instead of waiting for one group trunk group to reach capacity before it directs calls to the next, the Round Robin algorithm balances the call volume evenly across all group trunk groups.

Round Robin Scenario

A company has two Boston sites. Boston1 and Boston2 serve the company's full U.S. enterprise. The Enterprise Administrator sets up a Round Robin scheme that pushes the first call to Boston1, the second to Boston2, the third call to Boston1, and the fourth call to Boston2, and so on, alternating between the two to deliver calls continuously.

% Allocation

With the % Allocation algorithm, Enterprise Administrators can assign a percentage of the incoming calls to each group trunk group in the trunk call routing scheme.

The % Allocation algorithm then routes calls to each group trunk group according to the percentages. If a selected group trunk group isn't available or is at maximum capacity, AT&T IP Flexible Reach selects the next group trunk group based on the percentage of allocation of the remaining available group trunk groups.

If a group trunk group is removed from a % Allocation routing scheme, IP Flexible Reach redistributes its percentage over the remaining group trunk groups in the scheme.

% Allocation Scenario

A company has two call centers: Call Center 1 is a small call center and Call Center 2 is a large call center. The Enterprise Administrator wants to route 10% of the call volume to Call Center 1 and 90% of the call volume to Call Center 2.

First, the Enterprise Administrator creates a new trunk call routing scheme with % Allocation routing algorithm, and then assigns the group trunk groups for Call Center 1 and Call Center 2. The percentages are assigned 10% to Call Center 1 and 90% to Call Center 2. The sum of allocations must always equal 100%.

Most Idle

With the Most Idle algorithm, calls are routed to the least used group trunk group at any given time. Like the other algorithms, the Most Idle algorithm offers failover rerouting that's triggered when the first group trunk group in the trunk call routing scheme is unavailable or at maximum capacity.

Most Idle schemes are useful if an Enterprise Administrator wants to balance active call traffic across SIP trunks. The Most Idle algorithm counts active calls, and then sends a new call to the trunk with the fewest active calls.

The Most Idle algorithm assumes that there will never be a time when all trunk groups are running at, or near, capacity.

Most Idle Scenario

In an enterprise using AT&T IP Flexible Reach, a part of the enterprise served by Call Center 1 is having a town hall meeting, so Call Center 1 is very busy. Call Center 2, which serves the rest of the enterprise, is not busy. To let Call Center 2 help with the heavy call traffic, the Enterprise Administrator sets up a Most Idle scheme. Call Center 2 will pick up overflow traffic.