I need a library that is able to open a PPP link for Internet access over a GSM infrastructure. The implementation MUST use only standard AT commands and PPP commands, and be written in C only. The library should also be able to suspend the link, be able to return to AT commands operation and resume the link.
IP/UDP layer over the PPP is required also, so that I need a function to open a UDP port, send a packet over IP over PPP and also receive data from the GSM network. The testing can be done on a standard PC, but the implementation MUST not depend on Windows or PC environment at all. Also, memory consumption must be kept to the very minimum (the library shall run on PIC microcontroller, I can give around 50 bytes of working memory data)