Can anyone tell me about MLX-10DS phones? I was told the S stands for security. Thanks in advance.

Heard of 10's/10d and 10dp never 's
Is it a special use phone custom made .

Actually they show up in
Magix docs as p//n

3156-03s / 107185076 / 7712d02d1-003

as inactive secure telephones also 20-ls/and 28-ls

maybe they were supplied to Nsa ??