Received an emergency telephone system repairs call out to a company in Banbury, North Oxfordshire that had no dial tone on any phones. After a short conversation with their I.T engineer we established it was a telephone system fault. An engineer was sent out equip with a temporary system and phones to get them going again. As suspected their system, an Avaya IP Office 500 had a blown power supply. ( Version 1 IPO 500 were notorious for this). Rather than ship the system for repair –approx 10 days we sourced a second user V2 chassis for the same money which takes the same modules and had them back up as before in less than 48 hours. 
The end user was delighted since the V2 had the upgrade path they were looking at, for adding remote IP extensions and SIP trunks. We recommended to the IT support to consider installing a UPS and have the phone system run off it since the vast majority of PBX breakdowns are from power outages or spikes.
