Operating system name and version: FreeBSD 8.2
Version of smsd: 3.1.14
Smsd installed from: ports
Name and model of a modem / phone: Siemens MC75
Interface: USB

The modem doesn't send short messages. After restarting it sends some messages and then stops sending again. The modem had been working fine for 2 months before.
2012-04-23 18:30:00,2, smsd: Running as uucp:uucp.
2012-04-23 18:30:00,4, smsd: File mode creation mask: 022 (0644, rw-r--r--).
2012-04-23 18:30:00,5, smsd: Outgoing file checker has started. PID: 27378.
2012-04-23 18:30:00,5, GSM1: Modem handler 0 has started. PID: 27379.
2012-04-23 18:30:00,5, GSM1: Using check_memory_method 1: CPMS is used.
2012-04-23 18:30:00,3, GSM1: Unexpected input: ^SYSSTART
2012-04-23 18:30:02,5, GSM1: Modem needs PIN, entering PIN...
2012-04-23 18:30:13,5, GSM1: CGSN: ***
2012-04-23 18:30:13,5, GSM1: IMSI: ***
2012-04-23 18:30:24,5, GSM1: SMS sent, Message_id: 228, To: ***, sending time 24 sec.
2012-04-23 18:30:37,5, GSM1: SMS sent, Message_id: 229, To: ***, sending time 13 sec.
2012-04-23 18:30:44,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:30:54,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:31:04,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:31:14,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:31:24,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:31:35,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:31:45,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:31:55,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:32:05,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:32:16,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:32:27,3, GSM1: Couldn't open serial port /dev/cuaU0, error: No such file or directory, waiting 30 sec.
2012-04-23 18:32:57,3, GSM1: Unexpected input: ^SYSSTART
2012-04-23 18:32:59,5, GSM1: Modem needs PIN, entering PIN...
2012-04-23 18:33:25,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:33:35,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:33:46,3, GSM1: write_to_modem: error 6: Device not configured
2012-04-23 18:33:56,2, GSM1: PIN handling: expected READY, modem answered OK
2012-04-23 18:33:56,2, GSM1: Modem handler 0 terminated abnormally. PID: 27379.
2012-04-23 18:44:01,5, smsd: Moved file /var/spool/sms/outgoing/20120423184357_22660.sms to /var/spool/sms/checked