Trunk Management

Owned by PeterF (Deactivated)
Sept 06, 2016
3 min read

Overview

Noojee Campaigner has the ability to utilise multiple trunks when dialing. This  includes the ability to select a trunk based on the format of the phone number.  A classic use  of this technique is dialing mobile/cell phone numbers using a Mobile Gateway (aka SIM dialler, GSM Gateway).

Concurrent Channels

One of the key issue with trunk management is the number of concurrent channels that a given trunk supports. Noojee Campaigner is an agressive consumer of channels and this can sometimes cause un-intended side affects. A key issue is that Noojee Campaigner can consume all available channels which leaves no channels available for normal business calls.

Pooled/Predictive Dialers

Noojee Campaigner has several dialers built into the core system. The most agressive of these are the 'Pooled' and 'Preditive' Dialers. If you are having problems with congestion then the Dialer is the most likely cause of the issue.

You can currently indirectly influense the number of channels that the Pooled Dialer uses by setting the 'Min Pool Size' and the 'Pool Growth Ratio'. You can see how these two settings affect the Pooled Dialer in the 04. Campaign Template. The Predictive dialer dynamically allocates channels and will automatically slow down if it is seeing congestion.

Congestion Sysmptoms

When there are no channels available to make a call this is referred to as 'Congestion'.

Noojee Campaigner is not always able to directly detect Congestion as there are a number of related problems that present the same symptoms to Noojee Campaigner. For example congestion can be caused by the remote exchange having congestion issues. System faults can also exhibit themselves as a form of Congestion.

User symptom

When the dialer detects congestion it will report the following error:

'Too many failed dial attempts'

When this occurs the user needs to reset the dialer, which MAY clear the congestion depending on the source.

Resetting the Dialer

To deal with the various sources of Congestion the Dialer uses an heuristic which basically states that if the dialler gets more than 20 failed connection attempts in a row, the dialer will shutdown. In these circumstances the Agent will have to 'Stop' the dialer and reselect a campaign before the dialer re-commence. This 'resetting' of the system will often clear the source of the congestion and let the dialer resume operation. In some circumstances the underlying cause may not be temporary and restarting the dialer will not fix the problem. If this is the case then you need to request support to have the underlying problem investigated.

Retry attempts

In cases where the dialer has attempt a call and the call has failed due to Congestion then call will be treated as a simple no answer. No Answer calls are rescheduled for later retry according to the 'No Answer retry limit' and the 'No Answer retry Lock Time'.  The default value is three attempts and three hours. You can modify these values on a per  04. Campaign Template basis.

Fixing the source of the problem

Congestion can result from a number of source and the fix is different for each source. The following attempts to outline the causes in order of likelness and possible fixes.

Too few channels

The most common cause of congestion is that you do not have sufficient channels available on your trunk. As a rule of thumb you need 2.5 channels for each Agent. e.g. for 10 agents you need 25 channels.

You have three choices:

1) increase the number of available channels

2) reduce the over-dial ratio of the dialler

For SIP based lines there are a number of ways you can increase the number of channels (depending on the source of the constraint).

Some ITSP (VoIP providers) limit the number of concurrent calls you can place through their system. You can often get this number increased.

You can increased the size of the tail (in simple terms your internet connection) that you use to make calls over.

You can compress the calls

Constrained Invites

In some circumstances your ITSP may artifically constrain the number of SIP 'INVITES' that can be outstanding. In laymans terms this means that they restrict the number of calls that can be dialled but which haven't started ringing (not technically correct but close enough for you to get the idea).  Some ITSP can increase this number but you may have to move to a different ITSP. Noojee came make some recommendations.

Dial Errors

We have seen some ITSP that simply can't handle the high dial rate Noojee Campaigner can deliver. These ITSP will start reporting errors (typically 501 internal server error). In these cases you need to move to a new ITSP. Noojee came make some recommendations.