excuse my poor English,

Im developing C++ aplication and I want to use PPP protocol over a
GSM comunication line. I have an API with send and receive functions
for the GSM comunication.

I want to use a library for encapsulating data to send, and then send
to GSM, but I dont find any library for this purpose, so I need to
use the ppp daemon.

I search in the pppd man, and I see the pty with the record option and
then use the pppdump for view the file.

But I get lost when I try to implementate some solution.
How can I send data to the pppd and take the ppp-packed-data into a
file to send via API function? And How can I put the API receive data
(suposed to be ppp-packed-data) to the ppplink and take the unpacked