Customers who use PRI lines have to generously purchase phone numbers. For instance, an organization with 70 phones will need 70 phone numbers from its telco to cover its maximum simultaneous-use needs. It works out to one phone number for every physical device. Add to this, the expensive PRI interface cards for every line in addition to the PRI line rentals.
SIP trunks are software-centric that allows them to be far more flexible and scalable, which makes it convenient. Adding or reducing the number of calls a SIP trunk handles usually only takes a change in configuration.
For instance, if you want 70 people to use phones to make calls, all you need is a single SIP trunk to handle 70 or more simultaneous voice calls. You don’t need 70 phone numbers as a single number can be used.
Many a times, we come across organizations where they mention that their SIP calls aren’t of high quality. It is mainly because of the limitations in bandwidth and the fact that the bandwidth used for voice is shared with general Internet data. At times, it chokes and your voice calls don’t go through. In order to provide QoS, we bundle data along with the SIP trunking that doesn’t have Internet limitations.
The savings on the multiple PRI lines, additional hardware needed, convenience and quality that SIP offers obviously puts voice communication in favor of SIP trunks.