Methods for fabricating gas discharge tubes. In some embodiments, a method for fabricating a gas discharge tube (GDT) device can include providing or forming an insulator substrate having first and second sides and defining an opening. The method can further include providing or forming a first electrode and a second electrode. The method can further include forming a first glass seal between the first electrode and the first side of the insulator substrate, and a second glass seal between the second electrode and the second side of the insulator substrate, such that the first and second glass seals provide a hermetic seal for a chamber defined by the opening and the first and second electrodes.