diff --git a/pyModeS/decoder/allcall.py b/pyModeS/decoder/allcall.py
index 6e296ca..5f352f4 100644
--- a/pyModeS/decoder/allcall.py
+++ b/pyModeS/decoder/allcall.py
@@ -1,5 +1,75 @@
 """
-Decoding all call replies DF=11
+Decode all-call reply messages, with dowlink format 11
+"""
 
-[To be implemented]
-"""
+from pyModeS import common
+
+
+def _checkdf(func):
+    """Ensure downlink format is 11."""
+
+    def wrapper(msg):
+        df = common.df(msg)
+        if df != 11:
+            raise RuntimeError(
+                "Incorrect downlink format, expect 11, got {}".format(df)
+            )
+        return func(msg)
+
+    return wrapper
+
+
+@_checkdf
+def icao(msg):
+    """Decode transponder code (ICAO address).
+
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        string: ICAO address
+
+    """
+    return common.icao(msg)
+
+
+@_checkdf
+def interrogator(msg):
+    """Decode interrogator identifier code.
+
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        int: interrogator identifier code
+
+    """
+    # simply the CRC reminder
+    return common.crc(msg)
+
+
+@_checkdf
+def capability(msg):
+    """Decode transponder capability.
+
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        int, str: transponder capability, description
+
+    """
+    msgbin = common.hex2bin(msg)
+    ca = common.bin2int(msgbin[5:8])
+
+    if ca == 0:
+        text = "level 1 transponder"
+    elif ca == 4:
+        text = "level 2 transponder, ability to set CA to 7, on ground"
+    elif ca == 5:
+        text = "level 2 transponder, ability to set CA to 7, airborne"
+    elif ca == 6:
+        text = "evel 2 transponder, ability to set CA to 7, either airborne or ground"
+    elif ca == 7:
+        text = "Downlink Request value is 0,or the Flight Status is 2, 3, 4 or 5, either airborne or on the ground"
+    else:
+        text = None
+
+    return ca, text
diff --git a/pyModeS/decoder/surv.py b/pyModeS/decoder/surv.py
index 746f47f..ceec90c 100644
--- a/pyModeS/decoder/surv.py
+++ b/pyModeS/decoder/surv.py
@@ -1,5 +1,132 @@
 """
-Warpper for short roll call surveillance replies DF=4/5
+Decode short roll call surveillance replies, with downlink format 4 or 5
+"""
 
-[To be implemented]
-"""
+from pyModeS import common
+
+
+def _checkdf(func):
+    """Ensure downlink format is 4 or 5."""
+
+    def wrapper(msg):
+        df = common.df(msg)
+        if df not in [4, 5]:
+            raise RuntimeError(
+                "Incorrect downlink format, expect 4 or 5, got {}".format(df)
+            )
+        return func(msg)
+
+    return wrapper
+
+
+@_checkdf
+def fs(msg):
+    """Decode flight status.
+
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        int, str: flight status, description
+
+    """
+    msgbin = common.hex2bin(msg)
+    fs = common.bin2int(msgbin[5:8])
+    text = None
+
+    if fs == 0:
+        text = "no alert, no SPI, aircraft is airborne"
+    elif fs == 1:
+        text = "no alert, no SPI, aircraft is on-ground"
+    elif fs == 2:
+        text = "alert, no SPI, aircraft is airborne"
+    elif fs == 3:
+        text = "alert, no SPI, aircraft is on-ground"
+    elif fs == 4:
+        text = "alert, SPI, aircraft is airborne or on-ground"
+    elif fs == 5:
+        text = "no alert, SPI, aircraft is airborne or on-ground"
+
+    return fs, text
+
+
+@_checkdf
+def dr(msg):
+    """Decode downlink request.
+
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        int, str: downlink request, description
+
+    """
+    msgbin = common.hex2bin(msg)
+    dr = common.bin2int(msgbin[8:13])
+
+    text = None
+
+    if dr == 0:
+        text = "no downlink request"
+    elif dr == 1:
+        text = "request to send Comm-B message"
+    elif dr == 4:
+        text = "Comm-B broadcast 1 available"
+    elif dr == 5:
+        text = "Comm-B broadcast 2 available"
+    elif dr >= 16:
+        text = "ELM downlink segments available: {}".format(dr - 15)
+
+    return dr, text
+
+
+@_checkdf
+def um(msg):
+    """Decode utility message.
+
+    Utility message contains interrogator identifier and reservation type.
+
+    Args:
+        msg (str): 14 hexdigits string
+    Returns:
+        int, str: interrogator identifier code that triggered the reply, and
+        reservation type made by the interrogator
+    """
+    msgbin = common.hex2bin(msg)
+    iis = common.bin2int(msgbin[13:17])
+    ids = common.bin2int(msgbin[17:19])
+    if ids == 0:
+        ids_text = None
+    if ids == 1:
+        ids_text = "Comm-B interrogator identifier code"
+    if ids == 2:
+        ids_text = "Comm-C interrogator identifier code"
+    if ids == 3:
+        ids_text = "Comm-D interrogator identifier code"
+    return iis, ids, ids_text
+
+
+@_checkdf
+def altitude(msg):
+    """Decode altitude.
+
+    Args:
+        msg (String): 14 hexdigits string
+
+    Returns:
+        int: altitude in ft
+
+    """
+    return common.altcode(msg)
+
+
+@_checkdf
+def identity(msg):
+    """Decode squawk code.
+
+    Args:
+        msg (String): 14 hexdigits string
+
+    Returns:
+        string: squawk code
+
+    """
+    return common.idcode(msg)
diff --git a/tests/test_allcall.py b/tests/test_allcall.py
new file mode 100644
index 0000000..e727d4b
--- /dev/null
+++ b/tests/test_allcall.py
@@ -0,0 +1,13 @@
+from pyModeS import allcall
+
+
+def test_icao():
+    assert allcall.icao("5D484FDEA248F5") == "484FDE"
+
+
+def test_interrogator():
+    assert allcall.interrogator("5D484FDEA248F5") == 22
+
+
+def test_capability():
+    assert allcall.capability("5D484FDEA248F5")[0] == 5
diff --git a/tests/test_surv.py b/tests/test_surv.py
new file mode 100644
index 0000000..0286e27
--- /dev/null
+++ b/tests/test_surv.py
@@ -0,0 +1,22 @@
+from pyModeS import surv
+
+
+def test_fs():
+    assert surv.fs("2A00516D492B80")[0] == 2
+
+
+def test_dr():
+    assert surv.dr("2A00516D492B80")[0] == 0
+
+
+def test_um():
+    assert surv.um("200CBE4ED80137")[0] == 9
+    assert surv.um("200CBE4ED80137")[1] == 1
+
+
+def test_identity():
+    assert surv.identity("2A00516D492B80") == "0356"
+
+
+def test_altitude():
+    assert surv.altitude("20001718029FCD") == 36000