Hosted IP PBX Solutions are very similar to onsite IP PBX systems - except they are hosted in a datacenter rather than in your office. They are sometimes marketed as Cloud IP PBX. Hosted IP PBX Systems are operated in a very stable environment - in the cloud. This is a major advantage. And even more so if your company has multiple office locations: hosted IP PBX solutions allow free calls between locations (as all calls are routed over a single cloud IP PBX), saving you additional cost. If one office location has internet connectivity problems, other locations will not be affected.
To deploy pure IP PBX systems, you need local DID phone numbers and a reliable internet connection. Currently, there few Cambodian DID phone numbers available, albeit at very high prices making usage of pure IP PBX systems not very attractive yet.