Arduino Uno R3 w/ SIM 900 SMS: +CMS Error 515 / PS busy [solved]

Official Hardware Retired GSM Shield
1

Hello All,

I've been working hard to try to get my new Arduino Uno R3 mated with a seeed SIM 900 board to work and send SMS messages. If it's relevant, I'm using AT&T in the US. So far, I've got a serial terminal to the working, networked SIM 900 board from my laptop using SSCOM3.2. I know the board is working without SIM card issues because I can call my phone using ATD, call the SIM 900 board using my cell phone and receive the call, and I can read received SMS messages through the serial terminal. My issue is:

AT+CMGS="xxxxxxxxxx"

test [followed by CTRL-Z or by sending the 1A hex character]
+CMS ERROR: PS busy

The "PS busy" text code corresponds to "Error 515" as well. This sequence always returns this error, no matter what I seem to try. Any help, experience, or suggestions would be much appreciated. This is my first post here, so if I have left something important out, let me know and I'll provide it. Thank you.

2

I solved this after some more tinkering. The "PS busy" error message is somewhat misleading - what was actually occurring was the AT+CSCA the sim card had stored wasn't working correctly on the AT&T network - I just had to bugger with the formatting of the number. Solved.

3

Hi.
after a long investigation (including flashing new FW...) I figured out, that "CMS Error 515 / PS busy" is also issued, if the validity of a prepaid SIM-card is expired (even if there is still some money on it!). After I loaded again some € onto the card, it worked perfectly. This is really a nasty error-code...