sim900 & arduino mega

hello guys i am working with project with gsm sim900 and i would like to use arduino mega who whas more interrupt pins but the the library that i used which is GSMSHIELD-master doesnt work with mega i had de-comment for mega but nothing communication between the do you know to correct library or if i can find any other library



I am using the software from ITEAD, ITEADLIB_Arduino_SIMCom-master, because I have a board from ITEAD which contains a Mega2560 and a SIM900 module. The serial link to the SIM900 is Serial1.
This software also runs with an Arduino Mega2560 board.