Thank you very much for your information. I will dome some research about what line protectors I have to use.

Thank you for tha information. We are using this adapters on highway for emergency calls and the lines are long. The FXS ports are broken all the time by overvoltage on them. What do you suggest to protect these ports?

Thank you very much for your answer. How can I stop calls remotely when my SPA FXS port is broken? Do you know if the FXS ports have overload protection and if they have what the limit is? Thank you