A softphone is a software program that provides telephone functionality on a non-tel-
ephone device, such as a PC or PDA. So how do we recognize such a beast? What might
at first glance seem a simple question actually raises many. A softphone should probably
have some sort of dial pad, and it should provide an interface that reminds users of a
telephone. But will this always be the case?
The term softphone can be expected to evolve rapidly, as our concept of what exactly
a telephone is undergoes a revolutionary metamorphosis.* As an example of this evo-
lution, consider the following: would we correctly define popular communication
programs such as Instant Messenger as softphones?
IM provides the ability to initiate
and receive standards-based VoIP connections. Does this not qualify it as a softphone?
Answering that question requires knowledge of the future that we do not yet possess.
Suffice it to say that while at this point in time, softphones are expected to look and
sound like traditional phones, that conception is likely to change in the very near future.
As standards evolve and we move away from the traditional telephone and toward a
multimedia communications culture, the line between softphones and physical tele-
phones will become blurred indeed. For example, we might purchase a communica-
tions terminal to serve as a telephone and install a softphone program onto it to providethe functions we desire.
Having thus muddied the waters, the best we can do at this point is to define what the
term softphone will refer to in relation to this book, with the understanding that the
meaning of the term can be expected to undergo a massive change over the next few
years. For our purposes, we will define a softphone as any device that runs on a personal
computer, presents the look and feel of a telephone, and provides as its primary function
the ability to make and receive full-duplex audio communications (formerly known as
“phone calls”)† through E.164 addressing.‡