@datn @sabi Whereas in #Germany #ISDN was more of a norm than exception to the point that only senior citizens that only paid for the basic must-offer landline didn't have it...

In fact, ISDN phone system cablings are so common CPEs like AVM's "#FritzBox" still offer the S0 bus interface to this day since every small office used that - espechally when cordless #DECT systems weren't an option...