Verizon Wireless’s deployment of IMS (IP Multimedia Subsystem), to support its LTE roll-out with all-IP services, is just about the most advanced project of its kind in the world, so the US carrier’s suppliers and the results of its ‘big bang’ approach are closely watched by more cautious cellcos elsewhere. Being a frontrunner brings business benefits, such as the opportunity to deploy services no rival has. It also carries high risks, and any problem is closely scrutinized and criticized. So when Verizon suffered a major LTE outage earlier in the year, it hit the headlines and brought the aggression of the IMS strategy into question. The culprit, it emerged, was that undersung plague of the mobile data network, the ‘signalling…