diff --git a/hosts/telefonmann/default.nix b/hosts/telefonmann/default.nix
index ea7132a..ed6b015 100644
--- a/hosts/telefonmann/default.nix
+++ b/hosts/telefonmann/default.nix
@@ -146,6 +146,11 @@ in {
       # };
     };
 
+    phonebook = [
+      { name = "Oma"; numbers = { Mobil = "+49151..."; Zuhause = "+494..."; }; }
+      { name = "Opa"; numbers = { Zuhause = "+494..."; }; }
+    ];
+
     extensions = {
       "*99" = { mode = "page"; displayName = "Durchsage an alle"; };
       "*100" = { mode = "all"; displayName = "Alle rufen"; };
diff --git a/modules/voip/default.nix b/modules/voip/default.nix
index 5502160..e3e07ae 100644
--- a/modules/voip/default.nix
+++ b/modules/voip/default.nix
@@ -90,6 +90,13 @@ in {
           "= /intercom.xml"       = { alias = "${directory.intercomFile}"; extraConfig = "default_type text/xml;"; };
           "= /contacts.json"      = { alias = "${directoryJson}";          extraConfig = ''default_type application/json; add_header Access-Control-Allow-Origin "*";''; };
           "= /auth"               = { extraConfig = ''default_type text/plain; return 200 "AUTHORIZED";''; };
+        } // lib.optionalAttrs (cfg.phonebook != []) (
+          { "= /phonebook.xml" = { alias = "${directory.phonebookMenuFile}"; extraConfig = "default_type text/xml;"; }; }
+          // lib.listToAttrs (lib.imap0 (i: _: {
+            name  = "= /phonebook-${toString i}.xml";
+            value = { alias = "${lib.elemAt directory.phonebookDetailFiles i}"; extraConfig = "default_type text/xml;"; };
+          }) cfg.phonebook)
+        ) // {
           "/" = {
             root      = "${diagram.webRoot}";
             extraConfig = lib.optionalString (!hasRuntimeSecrets) "index index.html;";
diff --git a/modules/voip/options.nix b/modules/voip/options.nix
index affded6..8fe485e 100644
--- a/modules/voip/options.nix
+++ b/modules/voip/options.nix
@@ -306,6 +306,29 @@ in {
       });
     };
 
+    phonebook = lib.mkOption {
+      default     = [];
+      description = ''
+        External contacts shown in the phone directory. Example:
+        [
+          { name = "Oma"; numbers = { Mobil = "+49151..."; Zuhause = "+494..."; }; }
+          { name = "Opa"; numbers = { Zuhause = "+494..."; }; }
+        ]
+      '';
+      type = lib.types.listOf (lib.types.submodule {
+        options = {
+          name = lib.mkOption {
+            type        = lib.types.str;
+            description = "Contact name shown in the directory listing.";
+          };
+          numbers = lib.mkOption {
+            type        = lib.types.attrsOf lib.types.str;
+            description = ''Labelled phone numbers, e.g. { Mobil = "+49..."; Zuhause = "+49..."; }.'';
+          };
+        };
+      });
+    };
+
     voicemailCheckExtension = lib.mkOption {
       type        = lib.types.str;
       default     = "*97";
diff --git a/modules/voip/provisioning/directory.nix b/modules/voip/provisioning/directory.nix
index c5d7c4d..baaf656 100644
--- a/modules/voip/provisioning/directory.nix
+++ b/modules/voip/provisioning/directory.nix
@@ -4,6 +4,7 @@ let
   baseUrl = "http://${cfg.serverAddress}:${toString cfg.directoryPort}";
 
   hasPageExtensions = lib.any (e: e.mode == "page") (lib.attrValues cfg.extensions);
+  hasPhonebook      = cfg.phonebook != [];
 
   # Deduplicated directory entries: one per extension, using the displayName from
   # allPhones (all phones sharing an extension have the same displayName).
@@ -27,6 +28,11 @@ let
       <Name>Intercom / Durchsage</Name>
       <URL>${baseUrl}/intercom.xml</URL>
      </MenuItem>
+  '' + lib.optionalString hasPhonebook ''
+     <MenuItem>
+      <Name>Externes Telefonbuch</Name>
+      <URL>${baseUrl}/phonebook.xml</URL>
+     </MenuItem>
   '' + ''
     </CiscoIPPhoneMenu>
   '';
@@ -68,8 +74,42 @@ let
     </CiscoIPPhoneDirectory>
   '';
 
+  phonebookMenuXml = ''
+    <?xml version="1.0" encoding="UTF-8"?>
+    <CiscoIPPhoneMenu>
+     <Title>Externes Telefonbuch</Title>
+     <Prompt>Bitte wählen</Prompt>
+  '' + lib.concatStringsSep "\n" (lib.imap0 (i: contact: ''
+     <MenuItem>
+      <Name>${contact.name}</Name>
+      <URL>${baseUrl}/phonebook-${toString i}.xml</URL>
+     </MenuItem>
+  '') cfg.phonebook)
+  + ''
+    </CiscoIPPhoneMenu>
+  '';
+
+  mkContactXml = contact: ''
+    <?xml version="1.0" encoding="UTF-8"?>
+    <CiscoIPPhoneDirectory>
+     <Title>${contact.name}</Title>
+     <Prompt>Bitte wählen</Prompt>
+  '' + lib.concatStringsSep "\n" (lib.mapAttrsToList (label: number: ''
+     <DirectoryEntry>
+      <Name>${label}</Name>
+      <Telephone>${number}</Telephone>
+     </DirectoryEntry>
+  '') contact.numbers)
+  + ''
+    </CiscoIPPhoneDirectory>
+  '';
+
 in {
   menuFile      = pkgs.writeText "directory.xml"      menuXml;
   listFile      = pkgs.writeText "directory-list.xml" listXml;
   intercomFile  = pkgs.writeText "intercom.xml"       intercomXml;
+  phonebookMenuFile    = pkgs.writeText "phonebook.xml" phonebookMenuXml;
+  phonebookDetailFiles = lib.imap0 (i: contact:
+    pkgs.writeText "phonebook-${toString i}.xml" (mkContactXml contact)
+  ) cfg.phonebook;
 }