Is it possible to use a dynamic DNS service? Which are supported? DynDNS.it, No-IP?

By default, the SIM cards do not support operations with port forwarding and dynamic DNS services because they have dynamic private IP addresses with a firewall. However, if you want to use communication methods of that kind, you can simply activate the public fixed IP address service in the IoT Portal. You can find more information about the cost of the service here: https://www.thingsmobile.com/business/plans/public-fixed-ip-option.