The CMX625 is an integrated telecom tone generator, DTMF encoder/decoder and PCM Codec-Filter designed for ISDN interfaces, Wireless Local Loop and other digitised speech systems. The tone generator covers a wide range of pre-programmed tones used in analogue phone systems. Three outputs are provided: Ringing signals, In-band tones or FSK data, and 12kHz/16kHz Subscriber Metering pulses. The PCM Codec-Filter performs voice digitisation and reconstruction and incorporates band limiting and smoothing with selectable A-law or -law companding following ITU-T recommendation G.711. The DTMF decoder presents the serial bus interface with the DTMF dialling information received from the telephone user and the tone generator sends the appropriate DTMF tones to this POTS interface. Other tone standards supported are: Fax and Modem `answer' and `originate', ITU-T `R1' and `R2' signals, dual tones for CIDCW and 'On-Hook' signalling systems and sufficient tones for simple melody generation.