To accept the offer, the caller must explicitly respond to the offer using, e.g., DTMF signalling.

NBTel proposed MF signalling with ANI initially in lieu of CCS7 with Caller ID.

No respondent stated that it could not provide answer supervision when employing MF signalling.

Unitel pointed out that its concept of EEA differs; FGD uses in-band MF signalling, whereas Unitel has stipulated CCS7 signalling.

The Commission will also allow IXCs to interconnect their networks using MF signalling wherever CCS7 is not available.

The message preferably is transmitted by DTMF-signalling (4, 5).

All terminals involved in an established voice connection communicate with each other, for example, by means of a so-called multi-frequency signalling method (DTMF) for interrogation of the answering machine on the respective remote station.

Such a condition may be defined as incoming dial or ringing tones on the toll trunk, or as outgoing dual-tone multi-frequency (DTMF) tones on the toll trunk.

It is therefore strongly recommended that the equipment is set to use DTMF signaling for access to public or private emergency services.

They both use single-frequency signaling for transmission of supervisory information and multifrequency signaling for addressing information.