diff --git a/src/pEp/_pEp/user_interface.cc b/src/pEp/_pEp/user_interface.cc
deleted file mode 100644
index f31ad82..0000000
--- a/src/pEp/_pEp/user_interface.cc
+++ /dev/null
@@ -1,123 +0,0 @@
-// This file is under GNU Affero General Public License 3.0
-// see LICENSE.txt
-
-// System
-#include <cassert>
-
-// local
-#include "user_interface.hh"
-
-namespace pEp {
-    namespace PythonAdapter {
-        using namespace std;
-        using namespace boost::python;
-
-        UserInterface *UserInterface::_ui = nullptr;
-
-        UserInterface::UserInterface() {
-            if (_ui)
-                throw runtime_error("only one UserInterface thread allowed");
-            _ui = this;
-        }
-
-        UserInterface::~UserInterface() {
-            _ui = nullptr;
-        }
-
-        UserInterface_callback::UserInterface_callback(PyObject *self) :
-                UserInterface(), _self(self) {
-//    adapter.ui_object(self);
-//    PEP_STATUS status = ::register_sync_callbacks(Adapter::session(),
-//            (void *) this, _notifyHandshake, retrieve_next_sync_event);
-//    assert(status == PEP_STATUS_OK);
-//    if (status)
-//        _throw_status(status);
-        }
-
-        UserInterface_callback::~UserInterface_callback() {
-//    ::unregister_sync_callbacks(Adapter::session());
-        }
-
-        PEP_STATUS UserInterface::_notifyHandshake(
-                pEp_identity *me, pEp_identity *partner,
-                sync_handshake_signal signal
-        ) {
-            if (!(me && partner))
-                return PEP_ILLEGAL_VALUE;
-
-            auto that = dynamic_cast< UserInterface_callback * >(_ui);
-            that->notifyHandshake(Identity(me), Identity(partner), signal);
-
-            return PEP_STATUS_OK;
-        }
-
-        void UserInterface::deliverHandshakeResult(int result, object identities) {
-            identity_list *shared_identities = nullptr;
-            if (identities != boost::python::api::object() && boost::python::len(identities)) {
-                shared_identities = new_identity_list(nullptr);
-                if (!shared_identities)
-                    throw bad_alloc();
-
-                try {
-                    identity_list *si = shared_identities;
-                    for (int i = 0; i < boost::python::len(identities); ++i) {
-                        Identity ident = extract<Identity>(identities[i]);
-                        si = identity_list_add(si, ident);
-                        if (!si)
-                            throw bad_alloc();
-                    }
-                }
-                catch (exception &ex) {
-                    free_identity_list(shared_identities);
-                    throw ex;
-                }
-            }
-
-            PEP_STATUS status = ::deliverHandshakeResult(Adapter::session(),
-                                                         (sync_handshake_result) result, shared_identities);
-            free_identity_list(shared_identities);
-            _throw_status(status);
-        }
-
-//PEP_rating UserInterface::get_key_rating_for_user(string user_id, string fpr)
-//{
-//    PEP_rating result;
-//    PEP_STATUS status =
-//        ::get_key_rating_for_user(Adapter::session(),
-//                user_id.c_str(), fpr.c_str(), &result);
-//    _throw_status(status);
-//    return result;
-//}
-
-//SYNC_EVENT UserInterface::retrieve_next_sync_event(void *management, unsigned threshold)
-//{
-//    time_t started = time(nullptr);
-//    bool timeout = false;
-//
-//    while (adapter.queue().empty()) {
-//        int i = 0;
-//        ++i;
-//        if (i > 10) {
-//            if (time(nullptr) > started + threshold) {
-//                timeout = true;
-//                break;
-//            }
-//            i = 0;
-//        }
-//        nanosleep((const struct timespec[]){{0, 100000000L}}, NULL);
-//    }
-//
-//    if (timeout)
-//        return new_sync_timeout_event();
-//
-//    return adapter.queue().pop_front();
-//}
-
-        void UserInterface_callback::notifyHandshake(
-                Identity me, Identity partner, sync_handshake_signal signal) {
-            call_method<void>(_self, "notifyHandshake", me, partner, signal);
-        }
-
-    } // namespace PythonAdapter
-} // namespace pEp {
-
diff --git a/src/pEp/_pEp/user_interface.hh b/src/pEp/_pEp/user_interface.hh
deleted file mode 100644
index 59e17fe..0000000
--- a/src/pEp/_pEp/user_interface.hh
+++ /dev/null
@@ -1,61 +0,0 @@
-// This file is under GNU Affero General Public License 3.0
-// see LICENSE.txt
-
-#ifndef USER_INTERFACE_HH
-#define USER_INTERFACE_HH
-
-// System
-#include <csetjmp>
-
-// Engine
-#include <pEp/sync_api.h>
-#include <pEp/message_api.h>
-
-// local
-#include "pEpmodule.hh"
-
-
-namespace pEp {
-    namespace PythonAdapter {
-
-        class UserInterface {
-            static UserInterface *_ui;
-        public:
-            UserInterface();
-
-            virtual ~UserInterface();
-
-            virtual void notifyHandshake(
-                    Identity me,
-                    Identity partner,
-                    sync_handshake_signal signal) {
-                throw runtime_error("override this method");
-            }
-
-            virtual void deliverHandshakeResult(int result, object identities);
-
-//     PEP_rating get_key_rating_for_user(string user_id, string fpr);
-
-        protected:
-            static PEP_STATUS _notifyHandshake(pEp_identity *me, pEp_identity *partner, sync_handshake_signal signal);
-        };
-
-        class UserInterface_callback : public UserInterface {
-            PyObject *_self;
-        public:
-            UserInterface_callback(PyObject *self);
-
-            ~UserInterface_callback();
-
-            void notifyHandshake(
-                    Identity me,
-                    Identity partner,
-                    sync_handshake_signal signal
-            );
-        };
-
-    } /* namespace PythonAdapter */
-} /* namespace pEp */
-
-#endif /* USER_INTERFACE_HH */
-