VoIP Gateways Article

VoIP gateways create bridges between legacy and IP-based technologies. And they can be used in a variety of applications.

Those applications include connecting a PSTN line to an IP PBX (News - Alert), linking analog devices to IP PBXs, bringing together PBXs with SIP trunks, and allowing for the soft migration of organizations to VoIP solutions.

Sometimes customers with older PBX equipment want to connect to IP-based connections. And VoIP gateways allow for that. But sometimes the situation is completely reversed.

As beroNet explains in a recent posting, sometimes organizations have public switched telephone network phone lines to which they already subscribe. That may be an analog line or lines, or connections based on ISDN technology. But sometimes these same organizations have PBXs based on newer, IP-based technology. As a result, these organizations need to make sure their traditional on-premises equipment can speak the same language as their newer (and probably more low-cost) IP-based connections. A VoIP gateway allows for that.

There are two kinds of ISDN, by the way. One offers a basic rate interface, or BRI. The other is known as primary rate interface, or PRI; that’s known as an E1 in Europe and as a T1 in the United States. A BRI line can support two simultaneous calls. A PRI line allows for up to 30 simultaneous calls.

If the client can make eight concurrent calls, that customer probably has four BRI lines, beroNet explains. In that case, the organization will need a four BRI gateway. However, beroNet adds, if the PBX has two PRI lines, a two PRI gateway is what’s called for.

But if the customer is using an analog line to connect with the IP PBX, that client will require an FXO gateway.

Speaking of analog, some companies have IP PBXs, and want to connect those with their existing analog endpoints. That way they don’t have to replace every deskphone on every desk in their offices, as well as analog alarm systems, doorphones, fax machines, and payment machines.

To allow for analog endpoint to IP PBX connections, beroNet offers an FXS gateway. beroNet describes this scenario as its hybrid module. And that allows users to connect two analog devices and two BRI lines to an IP PBX.

beroNet adds that, as customers move to IP-based technology, they need not do it all at once. Instead, they can do so-called soft migrations.           

“The beroNet ISDN gateways can work in NT or TE, meaning that they can simulate the ISDN provider or the PBX,” beroNet explains. “If the PBX used in the soft migration is an ISDN one, then you need to find out the type of lines it is connected to  (BRI or PRI). Once we know the type of lines and the number of lines we know the kind of gateway we’ll need. [For] example: if the PBX has 1 PRI, you will need a gateway with 2 PRI (one port in each direction).”