TELECOM Digest OnLine - Sorted: Re: Cut-Through Connection

Re: Cut-Through Connection

Paul A Lee (
Wed, 3 Nov 2004 12:27:08 -0500

In TELECOM Digest V23 #528, (Ariel
Burbaickij) wrote (in part):

> Could someone explain to me what does the term "cut-through
> connection" mean? Are there several meanings?

In general, "cut-through" is the action of connecting one circuit to
another circuit (subscriber line, tie trunk, tandem trunk, etc.). In
electromechanical switches, dial pulses were presented sequentially
and acted on the switching equipment sequentially. The speed with
which each incremental connection was cut-through affected the path
of the subsequent dial pulses.

With electronic switching and senderized (rather than individual)
presentation of pulses or tones, "cut-through" has come to refer o the
point at which a station-to-station or station-to-facility voice path
is established, following the sending of pulses or DTMF or MF) tones.

For example, when you dial a DID number served by an analog DID trunk,
the connection between your phone and the DID trunk is not cut through
until after the end office switch has DTMF'd the DID station number to
the prem switch. That's why you don't hear the tones (or pulses, if
it's an old prem switch) being sent.

I have also heard the term "cut-through" used to refer to the opening
of a voice path laid out by out-of-band signaling (SS7 or
ISDN). Technically inaccurate, but conceptually plausible, so it will
probably stick.

(I know telco veterans' explanations will differ from mine on several
points, but not fundamentally.)

Paul A Lee Sr Telecom Engineer <>
Rite Aid Corporation HL-IS-COM (Telecomm) V: +1 717 730-8355
30 Hunter Lane, Camp Hill, PA 17011-2410 F: +1 717 975-3789
P.O. Box 3165, Harrisburg, PA 17105-3165 W: +1 717 805-6208

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