diff --git a/.circleci/config.yml b/.circleci/config.yml
index d7d80ca..65a3521 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -3,6 +3,7 @@ workflows:
   version: 2
   test:
     jobs:
+      - test-3.10
       - test-3.9
       - test-3.8
       - test-3.7
@@ -13,9 +14,9 @@ workflows:
       - test-pypy3
       - test-pypy2
 jobs:
-  test-3.9: &test-template
+  test-3.10: &test-template
     docker:
-      - image: python:3.9 # We run one test in non-alpine environment, just in case
+      - image: python:3.10 # We run one test in non-alpine environment, just in case
     working_directory: ~/work
     steps:
       - checkout
@@ -36,6 +37,10 @@ jobs:
           command: |
             . venv/bin/activate
             pytest -v
+  test-3.9:
+    <<: *test-template
+    docker:
+      - image: python:3.9-alpine
   test-3.8:
     <<: *test-template
     docker:
diff --git a/setup.py b/setup.py
index eb6371f..51f188d 100644
--- a/setup.py
+++ b/setup.py
@@ -13,7 +13,7 @@
 setup(
     name='smpplib',
     version='2.2.1',
-    url='https://github.com/podshumok/python-smpplib',
+    url='https://github.com/python-smpplib/python-smpplib',
     description='SMPP library for python',
     packages=find_packages(),
     install_requires=['six'],
diff --git a/smpplib/client.py b/smpplib/client.py
index bb44b04..ebad492 100644
--- a/smpplib/client.py
+++ b/smpplib/client.py
@@ -207,39 +207,43 @@ def send_pdu(self, p):
             ))
 
         self.logger.debug('Sending %s PDU', p.command)
-
         generated = p.generate()
-
         self.logger.debug('>>%s (%d bytes)', binascii.b2a_hex(generated), len(generated))
 
-        sent = 0
+        try:
+            self._socket.sendall(generated)
+        except socket.error as e:
+            self.logger.warning(e)
+            raise exceptions.ConnectionError()
+
+        return True
 
-        while sent < len(generated):
+    def _recv_exact(self, exact_size):
+        """
+        Keep reading from self._socket until exact_size bytes have been read
+        """
+        parts = []
+        received = 0
+        while received < exact_size:
             try:
-                sent_last = self._socket.send(generated[sent:])
+                part = self._socket.recv(exact_size - received)
+            except socket.timeout:
+                raise
             except socket.error as e:
                 self.logger.warning(e)
                 raise exceptions.ConnectionError()
-            if sent_last == 0:
+            if not part:
                 raise exceptions.ConnectionError()
-            sent += sent_last
-
-        return True
+            received += len(part)
+            parts.append(part)
+        return b"".join(parts)
 
     def read_pdu(self):
         """Read PDU from the SMSC"""
 
         self.logger.debug('Waiting for PDU...')
 
-        try:
-            raw_len = self._socket.recv(4)
-        except socket.timeout:
-            raise
-        except socket.error as e:
-            self.logger.warning(e)
-            raise exceptions.ConnectionError()
-        if not raw_len:
-            raise exceptions.ConnectionError()
+        raw_len = self._recv_exact(4)
 
         try:
             length = struct.unpack('>L', raw_len)[0]
@@ -247,18 +251,7 @@ def read_pdu(self):
             self.logger.warning('Receive broken pdu... %s', repr(raw_len))
             raise exceptions.PDUError('Broken PDU')
 
-        raw_pdu = raw_len
-        while len(raw_pdu) < length:
-            try:
-                raw_pdu_part = self._socket.recv(length - len(raw_pdu))
-            except socket.timeout:
-                raise
-            except socket.error as e:
-                self.logger.warning(e)
-                raise exceptions.ConnectionError()
-            if not raw_pdu:
-                raise exceptions.ConnectionError()
-            raw_pdu += raw_pdu_part
+        raw_pdu = raw_len + self._recv_exact(length - 4)
 
         self.logger.debug('<<%s (%d bytes)', binascii.b2a_hex(raw_pdu), len(raw_pdu))
 
diff --git a/smpplib/command.py b/smpplib/command.py
index b19b0c6..bde5840 100644
--- a/smpplib/command.py
+++ b/smpplib/command.py
@@ -410,7 +410,7 @@ class BindTransmitter(Command):
     )
 
     def __init__(self, command, **kwargs):
-        super(BindTransmitter, self).__init__(command, need_sequence=False, **kwargs)
+        super(BindTransmitter, self).__init__(command, **kwargs)
 
         self._set_vars(**(dict.fromkeys(self.params)))
         self.interface_version = consts.SMPP_VERSION_34
@@ -817,7 +817,7 @@ class DeliverSM(SubmitSM):
     )
 
     def __init__(self, command, **kwargs):
-        super(DeliverSM, self).__init__(command, need_sequence=False, **kwargs)
+        super(DeliverSM, self).__init__(command, **kwargs)
         self._set_vars(**(dict.fromkeys(self.params)))
 
 
@@ -900,7 +900,7 @@ class Unbind(Command):
     params_order = ()
 
     def __init__(self, command, **kwargs):
-        super(Unbind, self).__init__(command, need_sequence=False, **kwargs)
+        super(Unbind, self).__init__(command, **kwargs)
 
 
 class UnbindResp(Command):
@@ -919,7 +919,7 @@ class EnquireLink(Command):
     params_order = ()
 
     def __init__(self, command, **kwargs):
-        super(EnquireLink, self).__init__(command, need_sequence=False, **kwargs)
+        super(EnquireLink, self).__init__(command, **kwargs)
 
 
 class EnquireLinkResp(Command):
diff --git a/smpplib/tests/test_command.py b/smpplib/tests/test_command.py
index a0e2433..0c47891 100644
--- a/smpplib/tests/test_command.py
+++ b/smpplib/tests/test_command.py
@@ -1,11 +1,13 @@
 from smpplib import consts, exceptions
+from smpplib.client import Client
 from smpplib.command import DeliverSM
 
 import pytest
 
 
 def test_parse_deliver_sm():
-    pdu = DeliverSM('deliver_sm')
+    client = Client("localhost", 5679)
+    pdu = DeliverSM('deliver_sm', client=client)
     pdu.parse(
         b"\x00\x00\x00\xcb\x00\x00\x00\x05\x00\x00\x00\x00\x00\x00\x00\x01\x00"
         b"\x01\x0131600000000\x00\x05\x00XXX YYYY\x00\x04\x00\x00\x00\x00\x00"
@@ -26,7 +28,8 @@ def test_parse_deliver_sm():
 
 
 def test_unrecognised_optional_parameters():
-    pdu = DeliverSM("deliver_sm", allow_unknown_opt_params=True)
+    client = Client("localhost", 5679)
+    pdu = DeliverSM("deliver_sm", client=client, allow_unknown_opt_params=True)
     pdu.parse(b'\x00\x00\x00\xa8\x00\x00\x00\x05\x00\x00\x00\x00/p\xc6'
               b'\x9a\x00\x00\x0022549909028\x00\x01\x00\x00\x04\x00\x00'
               b'\x00\x00\x00\x00\x00\x00iid:795920026 sub:001 dlvrd:001 '
@@ -37,7 +40,7 @@ def test_unrecognised_optional_parameters():
     # This is only to avoid a breaking change, at some point the other behaviour
     # should become the default.
     with pytest.raises(exceptions.UnknownCommandError):
-        pdu2 = DeliverSM("deliver_sm")
+        pdu2 = DeliverSM("deliver_sm", client=client)
         pdu2.parse(b'\x00\x00\x00\xa8\x00\x00\x00\x05\x00\x00\x00\x00/p\xc6'
                   b'\x9a\x00\x00\x0022549909028\x00\x01\x00\x00\x04\x00\x00'
                   b'\x00\x00\x00\x00\x00\x00iid:795920026 sub:001 dlvrd:001 '