Operating system name and version: Ubuntu 18.04.2 LTS
Version of smsd: Version 3.1.21
Smsd installed from: package repository
Name and model of a modem / phone: Huawei e3372
Interface: USB

Near a month sms gateway working properly, but now it doesn't work..smsd.log files like below...sms stores in the queue folder.What happened and how can fix it?
2019-08-01 10:19:27,5, GSM1: Modem handler 0 has started. PID: 6145. Will only send messages.
2019-08-01 10:19:27,5, GSM2: Modem handler 1 has started. PID: 6147. Will only send messages.
2019-08-01 10:19:27,5, GSM1: Serving queues: Dialog
2019-08-01 10:19:27,5, smsd: Outgoing file checker has started. PID: 6144.
2019-08-01 10:19:27,5, GSM2: Serving queues: Mobitel
2019-08-01 10:19:27,5, GSM3: Modem handler 2 has started. PID: 6148. Will only send messages.
2019-08-01 10:19:27,5, GSM3: Serving queues: All
2019-08-01 10:19:27,6, GSM1: Checking if modem is ready
2019-08-01 10:19:27,6, GSM3: Checking if modem is ready
2019-08-01 10:19:27,6, GSM2: Checking if modem is ready
2019-08-01 10:21:24,3, GSM1: Modem is not ready to answer commands (Timeouts: 22)
2019-08-01 10:21:24,2, GSM1: Failed to initialize modem GSM1. Stopping.
2019-08-01 10:21:24,2, GSM1: Modem handler 0 terminated. PID: 6145, was started 19-08-01 10:19:27, up 1 min.
2019-08-01 10:21:24,2, smsd: Modem handler 0 (GSM1) terminated while mainprocess is still running. Exited, status 127.
2019-08-01 10:21:24,3, GSM3: Modem is not ready to answer commands (Timeouts: 22)
2019-08-01 10:21:24,2, GSM3: Failed to initialize modem GSM3. Stopping.
2019-08-01 10:21:24,2, GSM3: Modem handler 2 terminated. PID: 6148, was started 19-08-01 10:19:27, up 1 min.
2019-08-01 10:21:24,3, GSM2: Modem is not ready to answer commands (Timeouts: 22)
2019-08-01 10:21:24,2, GSM2: Failed to initialize modem GSM2. Stopping.
2019-08-01 10:21:24,2, GSM2: Modem handler 1 terminated. PID: 6147, was started 19-08-01 10:19:27, up 1 min.
2019-08-01 10:21:25,2, smsd: Modem handler 1 (GSM2) terminated while mainprocess is still running. Exited, status 127.
2019-08-01 10:21:25,2, smsd: Modem handler 2 (GSM3) terminated while mainprocess is still running. Exited, status 127.
2019-08-01 10:21:37,5, smsd: SMS To: xxxxxxxxxx. Moved file /var/spool/sms/outgoing/send_Ixi93X to /var/spool/sms/Dialog

Thank You.