DB schema of gammu-smsd uses default values for date/time in SQLite3 that are stored in GMT instead of localtime.
The other databases (mysql & postgresql) already store the datetime in localtime.
This is somehow fixed in gammu-smsd with 234f630 but only for the gammu-smsd part. If anyone inserts data into the tables without setting a value of the datetime fields, the date will be GMT which is not consistent.
An example would be for example in table outbox, column InsertIntoDB. But this the case for all other columns in all tables. There the default value is set like this. NOT NULL DEFAULT (datetime('now'))
It should probably be NOT NULL DEFAULT (datetime('now', 'localtime')).
Unfortunately updating the default value of columns in sqlite3 is not supported by a single statement.