diff --git a/modules/initrd-contact-info.nix b/modules/initrd-contact-info.nix
index 60d15c8..69d9940 100644
--- a/modules/initrd-contact-info.nix
+++ b/modules/initrd-contact-info.nix
@@ -3,8 +3,9 @@
 { config, pkgs, lib, ... }:
 let
   contact_name = "Daniel Langbein";
-  # TODO: move phone number to secret file
-  contact_phone = "+49 xxx yyy";
+  # The file `phone-number` contains only one line with our phone number, e.g. +49 0173 ...
+  # Be aware that the phone number will be written to the nix store in plaintext!
+  contact_phone = (builtins.readFile ../secrets/phone-number);
   contact_mail = "daniel@systemli.org";
 
   # https://wiki.nixos.org/wiki/Shell_Scripts
@@ -36,7 +37,10 @@ let
   };
 in
 {
-  # Plymouth boot splash screen.
+  # We found no non-graphical solution to print the contact info with systemd initrd.
+  # Workaround: Run a dummy service that has the contact info as service name ...
+  #
+  # Alternative: Use Plymouth for a graphical boot splash screen.
   # TODO: Only on graphical installations!
   #
   # To see the splash screen. https://wiki.archlinux.org/title/Plymouth#Installation