System information

on any number of variables that are programmed into the system. This is especially
relevant in the context of features such as hot-desking.
Hot-desking is a feature that allows someone to log into a device and receive his calls
at that device. Let’s say we have three sales agents who typically work outside of the
office, but spend a couple of days each month in the office to do paperwork. Since they
are unlikely to be on-site at the same time, instead of having a separate telephone for
each of those three sales agents, they could share a single office phone (or on a larger
scale, a dozen folks could share a pool of, say, three phones). This scenario illustrates
the convenience (and necessity) of allowing the system to separate the concept of a user
and extension from the physical phone.
So what are some examples of bad names for telephone devices? Something like a per-
son’s name, such as [SimonLeBon], would be a poor name for a telephone as the phone
may also be used by Joan Jett and Rick Astley. The same reasoning can be applied to
why you would not want to name a phone based on an extension number: a phone
name of [100] would be a poor choice since you might want to reprovision the device
for extension 160 in the future, or it might be used by several people with different
extensions in a hot-desking solution. Using numeric account names is also very bad
from a security perspective and is discussed in more detail in Chapter 26.
A popular way to name a phone is using the MAC address of the device. This is a unique
identifier specific to the phone that follows it where it goes and doesn’t directly relate
to the user operating the phone or the extension number currently associated with it.
Some corporations have stickers they place on their equipment with a bar code and
other information that allows them to keep stock of provisioned equipment; these
unique codes would also be an acceptable choice to use for phone names as they don’t
provide any logical relation to a particular person, but do provide specific information
about the devices themselves.
The choice is yours as to how you want to name your phones, but we primarily want
to abstract any concept of the telephone being owned by a person, or even its location
in the network, since these concepts are outside the realm of Asterisk and can change
at any time.
Throughout this book, you’ll see us using phone names that look like MAC addresses
(such as 0000FFFF0001 and 0000FFFF0002) to differentiate between devices. You will want
to use phone names that match the hardware you are using (or some other string that
is unique to the device you are registering).
As a final consideration, we should make it clear that what we are suggesting regarding
device names is not a technical requirement. You are free to name your devices anything
you want, as long as they meet the requirements of Asterisk’s naming conventions for
devices (stay with alphanumeric characters with no spaces and you’ll be fine).
Telephone Naming Concepts | 85