What is differences between Digital (Solid State) and Analog (Gas)?
Digital (solid state) offers a quicker response time for special equipment such as PBX systems. Analog (gas tube) offers a higher current handling capability, however the response time is slower. (Normally used with voice lines)
Digital (solid state) protection is preferred over analog (gas tube) protection for EVERY application, EXCEPT for CAT5 / CAT5e. ALL T1, E1, xDSL (ADSL, HDSL, VDSL) lines are CAT3. Gas tubes are marketed as more robust than digital (solid state). Gas tubes will handle extremely high current surges (10,000 A) for 10 applications. Solid state devices will function once at this current, and then fuse to ground to minimize equipment damage. This level of current represents a direct or almost direct lightning strike. With a lightning strike of this nature, it is still better to have the faster reaction time of a solid state device, and replace a inexpensive module versus expensive line equipment.