SIP trunks are used to establish a connection between your organization's phone system and the public switched telephone network (PSTN) or other VoIP networks. They enable you to make and receive calls over the Internet.

The number of SIP trunks you need depends on your business's call volume. Typically, one SIP trunk can handle one concurrent call. To determine your needs, calculate your peak call volume and add some buffer capacity for scalability.

The cost of SIP trunks can vary widely depending on the provider, your location, and your specific needs. Typically, providers offer pricing based on the number of channels (concurrent calls) you require, and there may be additional fees for features and usage.

PRI (Primary Rate Interface) trunks are digital phone lines used in traditional telephony. They deliver multiple voice or data channels over a single physical connection and are often used by larger organizations for high call volume.

The main difference between SIP Trunk and PRI is the technology used. SIP trunks use the Internet and VoIP to transmit calls, offering more flexibility and scalability. PRI trunks, on the other hand, are traditional digital lines with a fixed number of channels and are typically used for higher call volume.

A Hosted PBX (Private Branch Exchange) is a cloud-based phone system where the PBX hardware and call management are hosted and maintained by a third-party provider. Users connect to the PBX via the Internet, eliminating the need for on-site hardware and reducing maintenance costs.

A Virtual PBX is another term for a Hosted PBX. It refers to a cloud-based phone system that offers PBX features without requiring on-site hardware.

A PBX switch, or Private Branch Exchange switch, is the core component of a phone system that routes calls internally within an organization. It connects internal extensions and manages incoming and outgoing calls.

No, Cloud PBX and VoIP are related but not the same. VoIP (Voice over Internet Protocol) is a technology that allows voice calls to be transmitted over the Internet, while Cloud PBX is a phone system that uses VoIP technology and is hosted in the cloud. Cloud PBX is one application of VoIP technology.