TELECOM Digest OnLine - Sorted: Re MF Tones - What are they currently being used for

Re MF Tones - What are they currently being used for

Bob Colby (rcolby@withheld)
Wed, 26 Jan 2005 18:35:40 -0600

[Pat - please suppress email address]

First, some terminology. R1 is the same as MF. R2 is MFC (Multi
Frequency Compelled, a two-way in-band signaling system used outside
of the US). See the appropriate ITU spec for more details (Q.310 and
Q.350 respectively).

R1/MF tones are still used extensively in the telecom network. Many
of the adjunct boxes use MF because it's simple to implement
(e.g. much simpler than using SS7), and most any system will support
it (certainly any switching system used in Region 1). The R1
interface is used on voice mail systems, prepaid/calling card boxes,
some E911 systems, etc.

The simple nature of R1/MF (complete en-bloc signaling, forward
direction only) allows small startups developing some new function in
a box to do what they need to do to interface to the network without
investing in SS7 solutions (which are getting to be less costly and
more of a commodity, but still require a LOT of testing and
integration to make them work correctly).

Like dial pulse, this interface will be around for a very long time.


Bob Colby

> X-Telecom-Digest: Volume 24, Issue 30, Message 7 of 20

> Hi everyone.

> I'm kind of curious about the MF tones I learned of recently, the ones
> that were used by the toll network of the 60's, 70's, and 80's to
> control how calls were routed.

> While I understand they are no longer used for call routing, are these
> tones still used today for other things, and if so, what? (I'm
> referring specifically to either the R1 or R2 tone plans, or something
> close to them.)

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