Switching to VoIP

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Chapter 12: PSTN Trunks

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Now you’ve got a fully functional gateway that answers your calls, rings your cell

phone when and if you want it to, and records a voice mail message if you’re

unavailable.

More on Trunk Sizing

T1 and its Euro-equivalent E1 provide 1.5 mbps and 2.0 mbps of bandwidth orga-

nized into 24 and 30 channels called DS0s. Throughout this book, we’ve referred pri-

marily to T1 circuits, since they are the most common form of digital dial-tone trunk.

But there are much higher capacity circuits available from your friendly local

exchange carrier that are based on the same technology. These hi-cap circuits are the

preferred way of hauling dial-tone from the LEC because they are generally less

costly for it and you to maintain. Still faster speeds are available using SONET opti-

cal carrier connections.

Unlike T1s, which are connected by two copper pairs, SONET con-

nections are made on multimode fiber-optic cable.

Once you decide how much capacity is needed at a PSTN connect point, you can

choose one of the T carrier or OC circuits described in Table 12-2.

Connecting Trunks to Your Telephone Network

Whether your PSTN trunks are PRI-signaled T1s, POTS lines, or VoIP trunks, there

are basically two ways to connect them to ...