Skills-Based Routing


Skills-based routing (SBR), or Skills-based call routing, is a call-assignment strategy used in call centres to assign incoming calls to the most suitable agent, instead of simply choosing the next available agent. It is an enhancement to the Automatic Call Distributor (ACD) systems found in most call centres. The need for skills-based routing has arisen, as call centres have become larger and dealt with a wider variety of call types.


In this respect, skills-based routing is also based on call distribution to agents through waiting queues, but one or many skills can be assigned to each agent, and call can be distributed to the most suitable agent.

In skills-based routing, you will have to find a way to be able to tag the call for a specific skill need. This can be done for example by entering the call distribution system using different incoming call numbers, using an IVR to let the caller do his own choice, or by requesting to the information system database the customer profile.


Skills-Based Routing

Getting Started

  • Create the skills

  • Apply the skills to the agents

  • Create the skill rule sets

  • Assign the skill rule sets using a configuration file

  • Apply the skill rule sets to call qualification, i.e. incoming calls by using the preprocess subroutine field

Note that you shouldn’t use skill based routing on a queue with queue members of type user because the behaviour is not defined and might change in a future XiVO version.


Skills are created using the menu Services ‣ Call center ‣ Skills. Each skill belongs to a category. First create the category, and in this category create different skills.

Note that a skill name can’t contain upper case letters and must be globally unique (i.e. the same name can’t be used in two different categories).


Skills Creation

Once all the skills are created you may apply them to agents. Agents may have one or more skills from different categories.


Apply Skills to Agents

It is typical to use a value between 0 and 100 inclusively as the weight of a skill, although any integer is accepted.

Skill Rule Sets

Once skills are created, rule sets can be defined.

A rule set is a list of rules. Here’s an example of a rule set containing 2 rules:

  1. WT < 60, english > 50

  2. english > 0

The first rule of this rule set can be read as:

If the caller has been waiting for less than 60 seconds (WT < 60), only try to call agents which have the skill “english” set to a value higher than 50; otherwise, go to the next rule.

And the second rule can be read as:

Only try to call agents which have the skill “english” set to a value higher than 0.

Let’s examine some simple scenarios, because there’s actually some subtilities on how calls are distributed. We will suppose that we have a queue with the default settings and the following members:

  • Agent A, with skill english set to 75

  • Agent B, with skill english set to 25

Scenario 1


  • Agent A is logged and not in use

  • Agent B is logged and not in use

  • There is no call in the queue

When a new call enters the queue, then it is distributed to Agent A. As long as Agent A is available and doesn’t answer the call, the call will never be distributed to Agent B, even after 60 seconds of waiting time.

When another call enters the queue, then after 60 seconds of waiting time, this call will be distributed to Agent B (and the first call will still be distributed only to Agent A).

The reason is that there’s a difference between a call that is being distributed (i.e. that is making agents ring) and a call that is waiting for being distributed. When a call is being distributed to a set of members, no other rule is tried as long as there’s at least 1 of these members available.

Scenario 2


  • Agent A is not logged

  • Agent B is logged and not in use

  • There is no call in the queue

When a new call enters the queue, then it is immediately distributed to Agent B.

The reason is that when there’s no logged agent matching a rule, the next rule is immediately tried.


Each rule set is composed of rules, and each rule has two parts, separated by a comma:

Each part contains an expression composed of operators, variables and integer constants.


The following operators can be used inside rules:

Comparison operators:

  • operand1 ! operand2 (is not equal)

  • operand1 = operand2 (is equal)

  • operand1 > operand2 (is greater than)

  • operand1 < operand2 (is lesser than)

Logical operators:

  • operand1 & operand2 (both are true)

  • operand1 | operand2 (at least one of them are true)

‘!’ is the operator with the higher priority, and ‘|’ the one with the lower priority. You can use parentheses ‘()’ to change the priority of operations.

Dynamic Part

The dynamic part can reference the following variables:

  • WT

  • EWT

The waiting time (WT) is the elapsed time since the call entered the queue. The time the call pass in an IVR or another queue is not taken into account.

The estimated waiting time (EWT) has never fully worked. It is mentioned here only for historical reason. You should not use it. It might be removed in a future XiVO version.


  • WT < 60

Skill Part

The skill part can reference any skills name as variables.

You can also use meta-variables, starting with a ‘$’, to substitute them with data set on the Queue() call. For example, if you call Queue() with the skill rule set argument equal to:


Then every $lang occurrence will be replaced by ‘german’.


Create Skill Rule Sets


  • english > 50

  • technic ! 0 & ($os > 29 & $lang > 39 | $os > 39 & $lang > 19)


Note that the expression:

english | french

is equivalent to:

english ! 0 | french ! 0

Sometimes, a rule references a skill which is not defined for every agent. For example, given the following rule:

english > 0 | english < 1

Then, for an agent which has the skill english defined, the result of this expression is always true. For an agent which does not have the skill english defined, the result of this expression is always false.

Said differently, an agent without a skill X is not the same as an agent with the skill X set to the value 0.

Technically, this is what is happening when evaluating the rule “english > 0” for an agent without the skill english:

  english > 0
=     <Substituing english with the agent value>
  "undefined" > 0
=     <A comparison with "undefined" in at least one operand yields undefined>
=     <In a boolean context, "undefined" is equal to false>

This behaviour applies to every comparison operators.

Also, the syntax that is currently accepted for comparison is always of the form:

variable cmp_op constant

Where “variable” is a variable name, “cmp_op” is a comparison operator and “constant” is an integer constant. This means the following expressions are not accepted:

  • 10 < english (but english > 10 is accepted)

  • english < french (the second operand must be a constant)

  • 10 < 11 (the first operand must be a variable name)

Apply Skill Rule Sets

A skill rule set is attached to a call using a bit of dialplan. This dialplan is stored in a configuration file you may edit using menu Services ‣ IPBX ‣ Configuration Files.


Use Rule Set In Dialplan

In the figure above, 3 different languages are selected using three different subroutines.

Each of this different selections of subroutines can be applied to the call qualifying object. In the following example language selection is applied to incoming calls.


Apply Rule Set to Incoming Call


Configuration file for simple skill selection :

exten = s,1,Set(XIVO_QUEUESKILLRULESET=english_rule_set)
same  =   n,Return()

exten = s,1,Set(XIVO_QUEUESKILLRULESET=french_rule_set)
same  =   n,Return()


You may monitor your waiting calls with skills using the asterisk CLI and the command queue show <queue_name>:

xivo-jylebleu*CLI> queue show services
services has 1 calls (max unlimited) in 'ringall' strategy (0s holdtime, 2s talktime), W:0, C:1, A:10, SL:0.0% within 0s
     Agent/2000 (Not in use) (skills: agent-1) has taken no calls yet
     Agent/2001 (Unavailable) (skills: agent-4) has taken no calls yet
  Virtual queue english:
  Virtual queue french:
     1. SIP/jyl-dev-assur-00000017 (wait: 0:05, prio: 0)

You may monitor your skills groups with the command queue show skills groups <agent_name>:

xivo-jylebleu*CLI> queue show skills groups <PRESS TAB>
agent-2   agent-3   agent-4   agent-48  agent-7   agent-1
xivo-jylebleu*CLI> queue show skills groups agent-1
Skill group 'agent-1':
  - bank           : 50
  - english        : 100

You may monitor your skills rules with the command queue show skills rules <rule_name>:

xivo-jylebleu*CLI> queue show skills rules <PRESS TAB>
english      french       select_lang
xivo-jylebleu*CLI> queue show skills rules english
Skill rules 'english':
  => english>90