SEEED SIM900 GSM Library with H/W serial


I'm trying to interface a SEED SIM900 GSM module to an Arduino MEGA. I can get it to work using simple AT commands via hardware RX1 and TX1 on the mega.

However I cannot get it to work using the GSM library which uses serial software. I have tried various connections between the boards but just seem to be able to get comms working between the SIM900 and the MEGA, very frustrating. Have looked at lots of articles on the web regards interfacing but none of them solve the problem.

Has anyone written a GSM library using H/W serial on a MEGA? It would make life much easier than having to create my own.

The reason for using the MEGA is that I have some other modules that use serial connections that I also want to interface to the MEGA, collect data and post the data on the web and the MEGA has 4 H/W UARTS so it makes sense to reduce processing overheads by using H/W UARTS.

Many Thanks