Does it work on all phone lines (PSTN ISDN etc)?
DSL works only on PSTN lines. It will not work on ISDN or on lines with carriers. It is compatible with eircom Phonewatch but may not be compatible with illegily connected alarm systems. It will work on lines that have a normal FAX connected (This might be a solution for a customer who thinks all their lines are ISDN as many of them have PSTN FAX lines).
