As a developer, you might be also interested what is planned to happen in next Gammu and Wammu releases, you can find this information in the roadmap.
Quite recently we started to merge all documentation sources listed bellow
(and other documents about internals and protocols) into single comprehensive
documentation. This is still not completely finished, however it already does
cover more topics than the old documentation bellow, though some are not
described that deeply. You can generate it using make devdoc-html
in build directory or browse it
online.
If you want to start writing something using Gammu, you should consider using
Python bindings. It provides easy to use bindings
in easy to use language. You can check module
documentation or some examples which are shipped in
python/examples directory in Gammu sources.
The libGammu API is meant for C developers who want to
use Gammu functionality, but also Gammu program or Gammu SMS Daemon are using this API. The API is documented in
Gammu API Documentation, which is automatically
generated using Doxygen. There are also some examples for using the API in
docs/develop/examples directory in Gammu sources.
The libGammu library internally uses also quite a lot of shared code and the are documented in Gammu internals documentation (generated using Doxygen).
Additional hints about protocols can be found in docs/develop in
Gammu sources or you might want to use git repository with various GSM documentation.
[GW]ammu