My project is about a 3G monitoring system and receiving SMS messages is crucial (= it is crucial not to miss any incoming SMS).


the problem as i see it is that you are mixing up receiving a SMS message notification with receiving serial data without losing characters.


the question really is
how can i receive serial data as a background process with out data loss ?
how can i signal foreground process that a message has been received and not lose messages?


a workable solution is a interrupt driven ringbuffer for serial reception
that signals the foreground with a flag on completion of notification message.


the ringbuffer must be large enough to allow processing without data loss
the chip must have adequate speed and resources [not a 690, more like 16f1829]
hserin is not in the solution , its not flexible enough to be useful for this sort of task


you will find ringbuffer examples on both forums