diff --git a/share/scripts/a_dtmf_phone.lua b/share/scripts/a_dtmf_phone.lua
new file mode 100644
index 0000000000..ccfea1a15c
--- /dev/null
+++ b/share/scripts/a_dtmf_phone.lua
@@ -0,0 +1,198 @@
+ardour {
+	["type"]    = "dsp",
+	name        = "ACE DTMF Phone",
+	category    = "Instrument",
+	license     = "MIT",
+	author      = "Ardour Team",
+	description = [[Ardour phone home]]
+}
+
+local r = 48000
+local p1 = 0
+local p2 = 0
+local tau = 2 * math.pi
+local active_note = -1
+local ringsize = 8
+
+function dsp_ioconfig ()
+	return {
+		{ midi_in = 1, audio_in = 0, audio_out = 1},
+		{ midi_in = 1, audio_in = 0, audio_out = 2}
+	}
+end
+
+function dsp_init (rate)
+	r = rate
+	-- allocate DSP -> GUI ringbuffer
+	self:shmem():allocate (1 + ringsize)
+	self:shmem():atomic_set_int (0, 0)
+	local buffer = self:shmem():to_int(1):array()
+	for i = 1, ringsize do
+		buffer[i] = -1 -- empty slot
+	end
+end
+
+-- https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling#Keypad
+local dtmf = {
+	["1"] = {1209, 697},
+	["2"] = {1336, 697},
+	["3"] = {1447, 697},
+	["A"] = {1633, 697},
+
+	["4"] = {1209, 770},
+	["5"] = {1336, 770},
+	["6"] = {1447, 770},
+	["B"] = {1633, 770},
+
+	["7"] = {1209, 852},
+	["8"] = {1336, 852},
+	["9"] = {1447, 852},
+	["C"] = {1633, 852},
+
+	["*"] = {1209, 941},
+	["0"] = {1336, 941},
+	["#"] = {1447, 941},
+	["D"] = {1633, 941},
+	[" "] = {0, 0},
+}
+
+local map = { "1", "2", "3", "4", "5", "6", "7", "8", "9", "0", "*", "#", "A", "B", "C", "D"}
+
+function midi_note_to_pad (n)
+	-- map [1..9 0 * #] to 12TET, ignore A..D
+	-- start at C == 1
+	return map [1 + n % 12]
+end
+
+function dsp_run (ins, outs, n_samples)
+	-- clear output buffer
+	local a = {}
+	for s = 1, n_samples do a[s] = 0 end
+
+	local function synth (s_start, s_end)
+		if active_note == -1 then
+			return
+		end
+
+		local f = dtmf[midi_note_to_pad (active_note)]
+		if f[1] == 0 then
+			return
+		end
+
+		local i1 = f[1] / r
+		local i2 = f[2] / r
+
+		for s = s_start,s_end do
+			a[s] = 0.5 * (math.sin (p1 * tau) + math.sin (p2 * tau))
+			p1 = p1 + i1
+			p2 = p2 + i2
+		end
+	end
+
+	local newdata = false
+	local tme = 1
+
+	for _,b in pairs (midiin) do
+		local t = b["time"] -- t = [ 1 .. n_samples ]
+		-- synth sound until event
+		synth (tme, t)
+		tme = t + 1
+		-- process MIDI events (ignore MIDI channel)
+		local d = b["data"] -- get midi-event
+		if (#d == 3 and (d[1] & 240) == 144) then -- note on
+			--if active_note == -1 then
+				active_note = d[2]
+				p1, p2 = 0, 0
+				-- inform UI
+				local pos = self:shmem():atomic_get_int (0)
+				local buffer = self:shmem():to_int(1):array()
+				buffer[1 + pos] = active_note
+				pos = (pos + 1) % ringsize
+				self:shmem():atomic_set_int (0, pos)
+				newdata = true
+			--end
+		end
+		if (#d == 3 and (d[1] & 240) == 128) then -- note off
+			if active_note == d[2] then
+				active_note = -1
+			end
+		end
+		if (#d == 3 and (d[1] & 240) == 176) then -- CC
+			if (d[2] == 120 or d[2] == 123) then -- panic
+				active_note = -1
+				-- clear UI
+				self:shmem():atomic_set_int (0, 0)
+				local buffer = self:shmem():to_int(1):array()
+				for i = 1, ringsize do
+					buffer[i] = -1 -- empty slot
+				end
+				newdata = true
+			end
+		end
+	end
+
+	-- synth rest of cycle
+	synth (tme, n_samples)
+
+	-- keep phase between 0..tau
+	p1 = math.fmod (p1, 1)
+	p2 = math.fmod (p2, 1)
+
+	-- set all outputs
+	for c = 1,#outs do
+		outs[c]:set_table (a, n_samples)
+	end
+
+	if newdata then
+		self:queue_draw ()
+	end
+end
+
+-----------------
+-- inline display
+-----------------
+
+local txt = nil -- a pango context
+local vpadding = 2
+local displayheight = 0
+local linewidth = 0
+
+function render_inline (ctx, displaywidth, max_h)
+	local pos = self:shmem():atomic_get_int(0)
+	local buffer = self:shmem():to_int(1):array()
+	local str = ""
+
+	for i = 1, ringsize do
+		local p = (i + pos + ringsize - 1) % ringsize
+		local n = buffer[1 + p]
+		if n ~= -1 and " " ~= midi_note_to_pad (n) then
+			str = str .. midi_note_to_pad (n)
+		end
+	end
+
+	if not txt then
+		txt = Cairo.PangoLayout (ctx, "Mono 10")
+		-- compute the size of the display
+		local siz = ""
+		for i = 1, ringsize do
+			siz = siz .. "0"
+		end
+		txt:set_text (siz)
+		local lineheight
+		linewidth, lineheight = txt:get_pixel_size()
+		displayheight = math.min (2 * vpadding + lineheight, max_h)
+	end
+
+	-- clear background
+	ctx:rectangle (0, 0, displaywidth, displayheight)
+	ctx:set_source_rgba (.2, .2, .2, 1.0)
+	ctx:fill ()
+
+	-- show dialed number
+	ctx:set_source_rgba (1.0, 1.0, 1.0, 1.0)
+	txt:set_text (str)
+	ctx:move_to (math.floor (.5 * (displaywidth - linewidth)), vpadding)
+	txt:show_in_cairo_context (ctx)
+
+	return {displaywidth, displayheight}
+end