Operating system name and version: Debian 9.11 (stretch)
Version of smsd: 3.1.15-2
Smsd installed from: package repository
Name and model of a modem / phone: Huawei E3531
Interface: USB

Hi, i am using smstools to have a communication fallback for times when I cannot reach my server over the internet. It means that I can request certain information by sms or do certain things by sending sms to the server.
It all works very well but there seems to be a certain amount of days until it stops working. This is frustrating because I plan on being away for some weeks and would like to rely on smstools.

My config looks like this:

How do I find out what's the problem and can have smstools running until forever?

Thanks a lot.