What are the Major Differences?
PRI
- PRI (Primary Rate Interface) is a physical connection to the PSTN over a dedicated line that only serves voice transmission.
- PRI uses a circuit switched model for making voice connections between people
- PRI has a guaranteed Quality of Service (QoS)
SIP Trunking
- SIP (Session Initiating Protocol) Trunking is a virtual connection to the PSTN over a physical line that is often shared over your existing data connection.
- SIP Trunking uses a packet switched model for making voice connections between people
- SIP Trunking is typically Best Effort
Let’s Talk – PRI
A PRI is a single line (typically a T1 connection in North America)
with 23 voice channels (and a single data/control channel), that allows
your business to hold 23 calls simultaneously. This is not always
equivalent to the number of phone numbers a business has. Your business
may have 100 phone numbers that are directed to come across a single
PRI, however, you will only be allowed to hold 23 phone conversations at
once.
Let’s Talk – SIP
In short, SIP Trunking is a method of sending your voice connection over
an existing data line, and therefore is commonly referred to as VoIP
(Voice over Internet Protocol).
Your call goes out over the SIP Trunk, is treated exactly like every
other piece of data on that connection and is not given priority over
webpages, emails, or instant messages.
Once it arrives at your carriers network over the SIP Trunk, your
provider’s equipment knows where to direct that call; this may either
switch it over to the PSTN (so that someone with a regular phone can
receive the call) or perhaps send it to a PBX at another location. A
single SIP Trunk is typically limited only by the amount of bandwidth on
your data connection, or in some cases, limited by the number of “call
paths” you are purchasing from your SIP Trunk provider.
