Lightbound IP Applications

We have had alot of conversation with SIP Long Distance providers lately, what we discovered is that all VoIP Service Providers are not the same.  Many resellers and wholesale providers actually provide service without having a Class 5 switch in there network.  They do this without the benefit of having a Class 5 switch.  What does this mean?  It means that the VoIP Service Providers can't give the same level of reliability, because their core switch is not redundant enough.  What I mean by this is, their switch cannot have any hardware or software failures without taking it down.  When looking at VoIP Service Providers ask if their switch is NEBS compliant and look under cover to make sure.