So you are convinced that Asterisk is the PBX telephony solution for your business. Now you need a place to host it. Obviously, you need some sort of dedicated platform to accommodate the administration and maintenance of Asterisk, so you are considering setting up a dedicated server on-site. However, have you considered the disadvantages of onsite hosting, especially with Asterisk?
First of all, your telephony system is going to be the communication front for your business. You want to give your patrons a great first impression. You won't achieve that if for some reason your Asterisk PBX is not performing to its full potential or available 100% of the time!
There are many points of failure, and while any one of these can be addressed to procure a more reliable situation (extra server, several redundant Internet providers, et. al.), it will cost a lot more money than you are probably willing to spend.
What advantages are there to using the VPS/Vserver solution?
In the case that you do suffer an interruption in service (power, Internet, etc.) at your office location, the Asterisk VPS/Vserver system will still answer and handle all of your incoming calls! Depending on your Asterisk configuration, those calls could be forwarded to a cellular phone, an alternate landline, or dumped into the voicemail system. Once services are restored at the office, everything bounces back to normal and you can retrieve any voicemails left during the outage. How does that sound for reliable service?
Sometimes there is still a necessity for an onsite Asterisk server, especially when using telephony hardware (ie. Digium cards). However, installations such as this can still benefit from the unmatched reliability and availability of a remote Asterisk VPS/Vserver to initially handle all incoming calls.