El telefonillo de intercambio HTA 811 reemplaza 8 generaciones anteriores de telefonillos Siedle instalados usando el sistema conocido como 6+n.replaces eight former generations of Siedle in-house telephones installed using what was known as the 6+n system. The overview illustrates what the compatible models look like and from when they were produced.
1952: LN 7145, LN 7150, S 7150 (alle Typen sind technisch und funktional gleichwertig)
