Telephony is one of those areas of life where, whether at home or at work, people do not like surprises. When people use phones, anything outside of the norm is an expectation not met, and as someone who is probably in the business of supplying telephone systems, you will know that expectations going unmet can lead to untold misery in terms of the extra work, lost money, and so forth that are associated with customer dissatisfaction.

In addition to ensuring that the user experience is in keeping with what users expect, there is also the need to make your Asterisk feel “at home.” For example, if an outbound call is placed over an analog line (FXO), Asterisk will need to interpret the tones that it “hears” on the line (busy, ringing, etc.).

By default (and maybe as one might expect since it was “born in the USA”), Asterisk is configured to work within North America. However, since Asterisk gets deployed in many places and (thankfully) people from all over the world make contributions to it, it is quite possible to tune Asterisk for correct operation just about anywhere you choose to deploy it.

If you have been reading this book from the beginning, chapter by chapter, you will have already made some choices during the process of installation and initial configuration that will have set up your Asterisk to work in your local area (and live up to your customers’ expectations).

Quite a few of the chapters in this book contain information that will help you internationalize^[89] or (perhaps more properly) localize your Asterisk implementation. The purpose of this chapter is to provide a single place where all aspects of the changes that need to be made to your Asterisk-based telephone system in this context can be referenced, discussed, and explained. The reason for using the phrase “Asterisk-based telephone system” rather than just “Asterisk” is that some of the changes will need to be made in other parts of the system (IP phones, ATAs, etc.), while other changes will be implemented within Asterisk and DAHDI configuration files.

Let’s start by getting a list together (in no particular order) of the things that may need to be changed in order to optimise your Asterisk-based telephone system for a given location outside of North America. You can shout some out if you like…

We’ll cover everything in this list, adopting a strategy of working from the outer edge of the system toward the very core (Asterisk itself). We will conclude with a handy checklist of what you may need to change and where to change it.

Although the principles discussed in this chapter will allow you to adapt your Asterisk specifically for your region (or that of your customer), for the sake of consistency all of our examples will focus on how to adapt Asterisk for one region: the United Kingdom.