SIP Trunking is the next evolution in the migration to VoIP. Until now, while your telephone system may be IP based your outside lines were still traditional analog or digital trunks. Not any more, now you can get Unity SIP Trunks so that you can make end-to-end VoIP calls.
SIP Trunks work more efficiently because they leverage your broadband or internet connection and not a series of fixed lines from the Telco.
Instead of oversubscribing the number of fixed lines you need to cover for that one very busy hour every day, you can pay for what you use most of the time and only pay on demand when you need to go over. This is called ‘bursting.’