Two years ago Telecom Italia has started a program to test fuel cell based systems as an alternative to batteries and gensets for the backup power requirements of the telecommunications industry. Fuel cell technology looks very promising for this application and several solutions are being proposed by various manufacturers, so Telecom Italia is continuing the program, testing different systems in order to evaluate their real performances and to determine parameters and requirements for a future standardization. All tests are performed in strict collaboration with the system's manufacturer and their results are shared and jointly evaluated. This paper deals with the tests performed on the ElectraGentrade system, manufactured by IdaTech and distributed in Italy by RENCO SpA. This system, expressly designed to provide stand-by power for critical power applications, uses a combination of a proton exchange membrane (PEM) fuel cell and energy storage devices (batteries or ultracapacitors) to provide uninterrupted backup power to an existing -48 volt DC power system. The system operates as a stand-by service and continuously monitors existing DC bus voltage. It can be configured both to respond instantly to voltage drops or for a delayed response to minimize fuel consumption when coupled with existing battery systems. The system is fueled by commercial grade (99.95% dry) hydrogen, supplied in standard hi pressure bottles or produced by a fuel processor via steam reforming of a water/methanol mixture. The fuel reformer guarantees extended run times with a very compact fuel source. All the safety issues resulting from the transport and storage of hi-pressure hydrogen are overridden. As in a previous paper on this matter, the joint-authorship approach provides unique perspectives from both the manufacturer, IdaTech, and the end-user, Telecom Italia Spa, across the phases of the field trials.