Who Should Read This Book

Telecom engineers—wired or wireless, circuit-switched, or packet-switched—should
be able to latch onto this introduction to the OpenBTS project. At the risk of spreading
the material too thin, care has been taken to explain both the radio and IP sides of
OpenBTS. If you are a radio frequency (RF) expert, you will learn something about
Internet telephony. If you are comfortable with SIP and RTP, you will pick up a thing
or two about radio systems and protocols.
Software engineers of baseband firmware, smartphone apps, or hosted services will learn
about how the mobile network itself can now be controlled and inspected at a very low
level. If you’re interested in debugging an application on a mobile device, OpenBTS
provides several raw interfaces to see exactly what’s going on over the air. There are also
new data APIs your software can consume to build applications for search-and-rescue,
emergency response, power optimization, roadway traffic analytics, etc.

Why I Wrote This Book

My background is mainly in VoIP. When I began working with OpenBTS, I was blissfully
unaware of how complex radio systems can be. Conversely, other people I was working
with were radio experts but had never touched VoIP. Documentation for the OpenBTS
project is plentiful but very broad to support this wide audience of interested parties; it
needed simplification.
We wanted a new book that would be able to give a complete newcomer to the technology
enough information to successfully set up their own network: get voice calls working,
exchange some SMS messages, etc. This initial success should then build confidence
and let that person set out on their own.
I’ve tried to mix a healthy amount of context into the step-by-step sections. Mobile
networks are still quite complex on the GSM and RF side. Every hint helps. I’m hoping
you will be able to avoid the large gotchas when setting yours up!
I also wanted the book to be interesting enough to read in the absence of hardware. This
book should give you enough information to scope the required resources before diving
into an OpenBTS-related project.