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Wallis Dudhnath - 4th April 2019  (14:51 GMT)

MFC R2 has stood the test of time.

Well before SS7 - Signalling System Number 7 - the main Signalling was MFC R2. MFC stands for Multi-Frequency Compelled and this means that for a request there must be
a response. It is a Request / Response signalling protocol. A R2 request will always need an acknowledgement (Ack). Thanks to R2 MFC we have the terms Forward and Backward signalling.

Before the arrival of digital Stored Program Control (SPC) and SS7, R2 MFC was used as a Register signalling system for Analog Telephone Exchanges. Unlike SS7 (out of band), R2 MFC
is an inband system that works within the range 300-3400MHz (or more).

At the time of writing (2019), MFC R2 is a legacy signalling that is used on several International

The bulk of CSPs - Communication Service Providers - are using SS7 / ISUP / Sigtran (IP).

VBR/ Wallis Dudhnath

Pronab Das - 15th June 2010  (06:26 GMT)

Hi Dear,
Can you give me full detail of of R2 MFC Signal,i want to know this signaling proses because i am working in a telecome company,because this company based on CTI(Computer Telephonic Intrigated)product,

K.F.K. - 7th May 2000  (23:34 GMT)

The R2 MFC is basically one of the standard signaling which can be used to establish a call between to different equipments such as, telephone switch with other one and PBX’s with local exchange. Using E1 or T1 connection. There is two main signaling, line signaling and register signaling. Line signaling is the one which send (seizer, seizer ack., release, clear back.etc.) signaling and Register signaling is the part that send the (A-number, B-number and the calling category).

Because of long call setup time and less call information in the R2 MFC, the most of connection today is using SS7 signaling which have more speed and features than R2 MFC signaling.

Etkphov - 29th April 2000  (23:34 GMT)

R2 MFC, Multi Frequency Compelled, is a widely spread signalling system. It has got its roots in the analog telecommunications world as it was developed for more than 30 years ago.

Due to its reliable operation and flexibility, it has been developed for both national and international usage. The signals are used to transfer the B-number as well as the category of the calling subscriber to the other exchange. In some cases, also the A-number is transferred. The R2 MFC signals code senders and code receivers to transfer the information between exchanges in the form of tones.

The 5 or 6 different tones frequencies are used. By combining these tones two and two can 10-15 different signals be coded.

Gopal Rane - 12th April 2000  (23:33 GMT)


R2 MfC signalling stands for Register(type2) Multiple frequency coding technique

MFC signaling is used for transfering of necessary information to establish a connection is performed on a general end-to-end basis by the compelled multifrequency coded register signals.

The first backward MFC signal has it own meaning and at the same time it serve as acknowledgement for the first forward MFC signal.

The frequencies of multifrequency (MFC) signals are the same as specified in the CCITT's recommendation Q.441.

For more detail please refer to Following ITU recommedation site


Eynchua - 8th April 2000  (23:31 GMT)

Can anybody tell me the detail definition of R2 MFC?

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