diff --git a/modules/nixos/services/asterisk-phony/default.nix b/modules/nixos/services/asterisk-phony/default.nix
new file mode 100644
index 0000000..4eb7d2a
--- /dev/null
+++ b/modules/nixos/services/asterisk-phony/default.nix
@@ -0,0 +1,31 @@
+{ inputs, config, lib, pkgs, ... }:
+let
+  cfg = config.services.asterisk-phony;
+in
+{
+  imports = [
+  ];
+
+  options.services.asterisk-phony = {
+    enable = lib.mkOption {
+      type = with lib.types; uniq bool;
+      default = false;
+      description = "Enable Asterisk Communication";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    services.asterisk = {
+      # See Configuration Options: https://search.nixos.org/options?channel=unstable&type=options&query=asterisk
+      enable = true;
+      confFiles = {
+        "pjsip.conf" = builtins.readFile  ./pjsip.conf;
+        "extensions.conf" = builtins.readFile ./extensions.conf;
+      };
+    };
+
+    # Firewall
+    networking.firewall.allowedTCPPorts = [ 8088 8089 ];
+    # networking.firewall.allowedUDPPorts = [ ... ];
+  };
+}
diff --git a/modules/nixos/services/asterisk-phony/extensions.conf b/modules/nixos/services/asterisk-phony/extensions.conf
new file mode 100644
index 0000000..d5a6a00
--- /dev/null
+++ b/modules/nixos/services/asterisk-phony/extensions.conf
@@ -0,0 +1,17 @@
+[from-internal]
+; dial the lecture rooms & backoffice
+; the syntax is NUMBER,SEQUENCE,FUNCTION
+; to call someone do Dial(MODULE/account, timeout)
+exten => 1001,1,Dial(PJSIP/saal1,20)
+exten => 1002,1,Dial(PJSIP/saal2,20)
+exten => 1600,1,Dial(PJSIP/backoffice,20)
+
+; Dial 100 for "hello, world"
+; this is useful when configuring/debugging clients (snoms)
+exten => 100,1,Answer()
+same  =>     n,Wait(1)
+same  =>     n,Playback(hello-world)
+same  =>     n,Hangup()
+; note: "n" is a keyword meaning "the last line's value, plus 1"
+; "same" is a keyword referring to the last-defined extension
+
diff --git a/modules/nixos/services/asterisk-phony/pjsip.conf b/modules/nixos/services/asterisk-phony/pjsip.conf
new file mode 100644
index 0000000..f532bfa
--- /dev/null
+++ b/modules/nixos/services/asterisk-phony/pjsip.conf
@@ -0,0 +1,51 @@
+; we use UDP for transport
+[transport-udp]
+type=transport
+protocol=udp
+bind=0.0.0.0
+
+; Note: this defines a macro, to shorten the config further down
+[endpoint_internal](!)
+type=endpoint
+context=from-internal
+disallow=all
+allow=ulaw
+
+[auth_userpass](!)
+type=auth
+auth_type=userpass
+
+[aor_dynamic](!)
+type=aor
+max_contacts=1
+
+
+; here come the definitions for our phones, using the macros from above
+
+; lecture hall 1
+[saal1](endpoint_internal)
+auth=saal1
+aors=saal1
+[saal1](auth_userpass)
+; well, maybe set a better password than this
+password=saal1
+username=saal1
+[saal1](aor_dynamic)
+
+; lecture hall 2
+[saal2](endpoint_internal)
+auth=saal2
+aors=saal2
+[saal2](auth_userpass)
+password=saal2
+username=saal2
+[saal2](aor_dynamic)
+
+[backoffice](endpoint_internal)
+auth=backoffice
+aors=backoffice
+[backoffice](auth_userpass)
+password=backoffice
+username=backoffice
+[backoffice](aor_dynamic)
+
diff --git a/systems/x86_64-linux/mow0m/default.nix b/systems/x86_64-linux/mow0m/default.nix
index 05bdde7..52b5e9c 100644
--- a/systems/x86_64-linux/mow0m/default.nix
+++ b/systems/x86_64-linux/mow0m/default.nix
@@ -56,6 +56,7 @@
   };
   programs.mosh.enable = true;
 
+  services.asterisk-phony.enable = true;
 
   # Firewall
   # networking.firewall.allowedTCPPorts = [ ... ];