GSM Modem | Microcontroller › 8051 › GSM Modem This topic has 1 reply, 2 voices, and was last updated 9 years, 2 months ago by Ashutosh Bhatt. Viewing 2 posts - 1 through 2 (of 2 total) Author Posts July 30, 2015 at 7:27 am #3789 SharonParticipant I want the SIM900 to automatically send sms to a number with a predefined text when a particular pin of the microcontroller is turned high . Is it possible using a AT89C51 microcontroller? July 31, 2015 at 11:05 am #13114 Ashutosh BhattParticipant yes its very easy GSM modem communicates through UART with AT89C51 u just follow our tutorials on interfacing GSM modem with AT89C51 Author Posts Viewing 2 posts - 1 through 2 (of 2 total) You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In