Corporate telephony systems have long abandoned the use of conventional analog lines in favor of ATX (automatic telephone exchange) paired with the connection to ISDN according to the PRI standards. However, not so long ago, a modern, cheaper, and more flexible way of establishing the office infrastructure appeared, which is called SIP-trunking. In this article, we will compare PRI connections with SIP trunks, highlighting both the advantages and drawbacks of the solution. PRI (Primary Rate Interface) is known to be a standard interface of the ISDN network.

Benefit #1 – Digital Telephony

It is important to understand that we are talking exclusively about digital signal transmission, but not analog. Both PRI and SIP standards use a digital signal model, with the only difference being that the ISDN PRI standard is considered to be a circuit-switched format, whereas cheap sip trunk is packet-switched.

Benefit #2 – Functionality

In terms of its work, if properly configured, both systems demonstrate high performance. Almost all IP ATAs on the market support PRI and SIP standards. The main idea of ​​the PRI interface (either E1 or T1 streams) is that within one digital line, 32 or 24 channels can be transmitted. Through them, voice message and synchronization info are transmitted. The T1 interface consists of 23 voice channels, with 1 channel being intended for synchronization. In turn, the E1 supports 30 voice channels, with 2 separate channels being allocated for signaling.

Benefit #3 – Pri Scalability

If you need to expand the number of channels, for example, to make them more than 30, then you are to add another PRI line. The situation of the company using from 1 to 4 PRI lines (E1 streams) on the ATX is quite common.

In a corporate network, the application of the SIP solution expands the tools of the administrator. A SIP trunk allows you to combine two remote offices as if they were connected by a physical line. One of the most important advantages of SIP trunks is the possibility of coexistence of transmission network traffic and that from telephony (VoIP) in one network transmission medium.

Why SIP?

As its name suggests, a SIP trunk operates on the basis of the SIP solution. According to its rules, telephone signaling, as well as voice messages, are formed into data packages and sent in a single network. The use of the SIP solution offers a wider range of possibilities compared to ISDN PRI. Besides, it also allows you to expand the fault tolerance parameters to all transmission channels.

In that way, SIP is extremely popular not only among large corporation but also among the smaller ones. The reason for it is that it allows conducting any necessary operations without any problems. Moreover, it is beneficial both in the financial and productive ways.