you have in your sim card 19 messages well received, but for the twentieth message displays errure 321
2010-01-04 11:25:29 [3737] [7] DEBUG: AT2[Huawei-E220]: --> AT+CMGR=20^M 2010-01-04 11:25:29 [3737] [7] DEBUG: AT2[Huawei-E220]: <-- AT+CMGR=20 2010-01-04 11:25:29 [3737] [7] DEBUG: AT2[Huawei-E220]: <-- +CMS ERROR: 321 2010-01-04 11:25:29 [3737] [7] ERROR: AT2[Huawei-E220]: CMS ERROR: +CMS ERROR: 321 2010-01-04 11:25:29 [3737] [7] ERROR: AT2[Huawei-E220]: CMS ERROR: I advice you to delet all messages but via MINICOM sudo apt-get install minicom --------------> / debian minicom-s select device / dev/ttyUSB0 after typing: AT + CMGD / / (command name in text: Delete message) ps:with minicom you would also initialization string for your modem
