I think that mil-spec or nuclear QC standards are probably overkill for civilian systems such as 911. Granted there should be some high standards in place, but the systems are a) not secret/classified and b) not as high liability. Yes, failure to handle a 911 call is serious problem, but not like a failed nuclear reactor shutdown in terms of cost, number of people affected, and as a last resort, ability to fall back to a paper-and-pen backup system.