Here I was learning RIL layer when some of the information links listed, only as a primer, when you know nothing about Ril can look at the following information, but really need to develop, then must be combined with code to spend time to familiar with debugging.
1.Android Layer Anatomy: http://wenku.baidu.com/link?url=biNzwBpZdgOqOfSeWSQMxy8w7-az4iZ8lbWviGYpnBh2L_ Dlbxt3ei5jo0hg8qpfdqmedvxcbr_k91rqixqcne9gujygaisdqg6g54mnvio
2.Framework Layer Ril control flow analysis; http://www.cnblogs.com/bastard/archive/2012/11/22/2783229.html
3.android Development Introduction: Http://wenku.baidu.com/link?url= 4waokpxqalzqgruqwsyo8rvmddqtxb-k54zaoamew9iba6b9rgg3acfdltyxrscbrnhhpj_fcycfdksbcunkbzulil3uwsmfeyhvvh6utuk
There are many repetitions, but there are other articles that are not spoken, so take a look at them all. It's best to look together with the code.
Android Ril Layer Anatomy