Caller ID: the difference between DTMF and FSK
DTMF vs FSK
There are two types of number recognition: via the regular fixed line you have to deal with DTMF, via cable telephony we speak of FSK. DTMF is only supported in the Netherlands and FSK in both the Netherlands and Belgium. In addition, DTMF works exclusively with KPN, while FSK works with all other providers.
DTMF is short for Dual Tone Multi Frequency. In the Netherlands, KPN is the only provider that uses DTMF for number recognition. If you have a subscription with KPN and a fixed telephone that supports FSK, number recognition does not work via the KPN network. Do you always want to be sure of number recognition at KPN? Then choose a fixed telephone that supports both DTMF and FSK.
FSK stands for Frequency Shift Keying and is used by providers such as Ziggo and Tele2. In Belgium too, mainly FSK is used. Compared to DTMF there are more possibilities at FSK than just number display. This way the name display can also be sent. If in doubt, always contact your provider. ** Please note: ** phones support FSK and / or DTMF only in the countries for which they were designed.