We are using a WP7504 on a mangOH Red. The modem is registered on the Sprint network.
I have an application that rapidly sends SMS messages with the AT+CMGS command. The module often hangs for an extended period of time after the CTRL-Z keystroke. I have noted 30+ seconds passing before I receive the OK result code.
This behavior is not consistent. It comes and goes in waves. The signal strength does not appear to be the issue–it is Good/Strong. I also tried resetting the antenna with cm radio off/on.
Is there any limit on how rapidly SMS messages can be sent? Even when adding a one-second delay between each command, I still see this behavior. I do not notice a delay when sending SMS messages manually from the AT command prompt.
Firmware Version: SWI9X15Y_07.12.09.00 r34123 CARMD-EV-FRMWR1 2017/04/26 23:34:19