On phone lines, the PTT (Telco) usually provides surge protection. It is one of the so called BORSCHT functions of every PSTN switch.
(BORSCHT – Battery / Overvoltage protection / Ringing / Supervision and etc…).
Ports can burn mainly due to two reasons:
1. bad overvoltage protection (lighting strike)
2. if you connect a phone line from Telco that provides BORSCHT to a FXS port at the PBX/Voice gateway, which provides BORSCHT as well.
There is no way to change the voltage, but the new Quintum series have commands to measure the line voltage and other valueable features.
APC produces good surge protectors for RJ-11, RJ-45 / RJ-48…
I do not answer via e-mail 🙂