Two Types of PBX
A hosted private branch exchange (PBX) provides PBX functionality (such as automated attendant, automatic call distribution, voicemail, call transfer, etc.) without having to own or maintain all necessary equipment onsite. A PBX works by routing calls to extensions while allowing your VoIP service provider to maintain all necessary equipment and software.
On-premise PBX is also known as an IP-PBX phone system. It is similar to a traditional PBX system that resides at a location, such as a computer equipment room or phone closet. The main difference is that IP routing is done with more current technology. The signal is done with an IP phone to the IP-PBX server using a LAN. Calls can go through a traditional phone company as well as voice over Internet (VoIP) using SIP trunking. Gateway cards are used to connect the system to the traditional phone company provider. The provider can be the one that already provides service, though a SIP trunk can be configured for use with an Internet service telephone provider (ISTP). An Asterisk-based system is the most affordable option for on-premise PBX due to the flexibility that is offered with open source software.
Pros and Cons
Includes “standard PBX” services, including voicemail, conference calls, and call records.
Can include add-on services such as conferencing or mobility features, depending on your business’s needs.
Not required to purchase, maintain or upgrade PBX equipments.
Power for equipment is not required.
Minimal on-site equipment is required, typically just handsets and a gateway.
High degrees of scalability and flexibility, depending on the vendor.
The potential for greater cost saving with bundling unified business communications
Quality of service(QoS) depends on the consistency of your connection to the vendor’s hosted service
The service provider maintains a high degree of control
Vendor feature an add-on service offerings can vary.
Pros and Cons
Having on-premise PBX gives user control to create, adjust and delete users as desired
New open source feature sets can be added without any license fees.
Current carrier does not have to be changed.
VoIP trunks can be added to save on calling costs.
Server ownership reduces expenses over time.
No DIY time on the part of the customer
Professional training of staff on new IP-PBX system is handled by the provider.
With SIP trunking, loss of Internet or catastrophic event has reduced the effect on operations because calls can be sent to another number or a mobile phone.
A technician may need to be called for upgrades and patches on software(and costs can be incurred).
Loss of power or PBX failure will result in callers not being able to get through, which stops business operations unless you have a SIP provider.