Anybody that tells you that business hosted PBX is a VoIP system is wrong. It can be one, but you would usually have to set it up with your provider to be such a service. Sometimes companies want everything over the Internet and others want something that is based on analog phones. There is no right or wrong way to choose which one to use; it depends entirely on the business and what they want.
The most important thing when choosing a provider for your business hosted PBX is to make sure that they are able to cater to your requests, because not every company is able to give you the same features. Every company has a focus of its own. The best way to determine whether a company can provide what you want is to look at what services they provide. Some provide a large variety of services and some are very limited. That generally answers your question of whether you can get business hosted PBX VoIP-based or not. Clearly it wouldn’t be called business hosted PBX.
A company calls the choice to switch from analog phones to VoIP phones a talk switch VoIP PBX. It’s where you can choose the way you connect. It gives you the chance to have the best of both worlds, especially if you can’t call 911 on a VoIP phone or if they don’t offer that option on the VoIP plan. All you would have to do is call 911 on a regular phone. On top of that, if a storm comes through, your phones are still able to connect, because they aren’t connected to a power source like a VoIP phone would be.
The ease of installment is another thing that people like about the switch VoIP PBX. A lot of companies do not like the difficulty of installment of some VoIP phones. Usually it requires somebody to come out to install everything and smooth it over with the business, but if everything comes in the mail and relies on people learning things themselves that is a deal breaker.
Choose a company that is willing to work within your requests and provide resources to make it a successful install and something that your employees will enjoy using.