diff --git a/cmake/BuildPJProject.cmake b/cmake/BuildPJProject.cmake
new file mode 100644
index 0000000..9838479
--- /dev/null
+++ b/cmake/BuildPJProject.cmake
@@ -0,0 +1,72 @@
+include(FetchContent)
+
+set(PJ_VERSION_TAG 2.16)
+
+
+
+set(PJ_REPO https://github.com/pjsip/pjproject.git)
+set(PJ_INSTALL_PATH ${PROJECT_SOURCE_DIR}/bin/pjproject/)
+
+set(PJ_CONFIG_CMD "configure --prefix=${PJ_INSTALL_PATH}")
+set(PJ_BUILD_CMD "make dep; make -j")
+
+message(STATUS "PJProject build information:")
+message(STATUS "Repo: ${PJ_REPO}")
+message(STATUS "Version: ${PJ_VERSION_TAG}")
+
+set(FETCHCONTENT_QUIET OFF)
+
+FetchContent_Declare(
+  PJProject
+  GIT_REPOSITORY ${PJ_REPO}
+  GIT_TAG ${PJ_VERSION_TAG}
+  GIT_PROGRESS ON
+)
+
+FetchContent_GetProperties(PJProject)
+
+if (NOT pjproject_POPULATED)
+  FetchContent_Populate(PJProject)
+endif()
+
+message(STATUS "PJProject sources at: ${pjproject_SOURCE_DIR}")
+message(STATUS "Start building PJProject...")
+
+execute_process(COMMAND "./configure --disable-pjsua2" WORKING_DIRECTORY ${pjproject_SOURCE_DIR} OUTPUT_VARIABLE exec_output_msgs)
+message("${exec_output_msgs}")
+execute_process(COMMAND make dep WORKING_DIRECTORY ${pjproject_SOURCE_DIR} OUTPUT_VARIABLE exec_output_msgs)
+message("${exec_output_msgs}")
+execute_process(COMMAND make WORKING_DIRECTORY ${pjproject_SOURCE_DIR} OUTPUT_VARIABLE exec_output_msgs)
+message("${exec_output_msgs}")
+
+file(GLOB PJ_LIB "${pjproject_SOURCE_DIR}/pjlib/lib/*pj-*")
+if (NOT PJ_LIB)
+  message(FATAL_ERROR "Couldn't find pj-lib compiled library.")
+endif()
+
+message(STATUS "pj-lib lib at: ${PJSUA_LIB}")
+
+file(GLOB PJSUA_LIB "${pjproject_SOURCE_DIR}/pjsip/lib/*pjsua-*")
+
+if (NOT PJSUA_LIB)
+  message(FATAL_ERROR "Couldn't find pjsua compiled library.")
+endif()
+
+message(STATUS "pjsua lib at: ${PJSUA_LIB}")
+
+add_library(pjproject::pj STATIC IMPORTED)
+set_target_properties(pjproject::pj PROPERTIES
+  IMPORTED_LOCATION ${PJ_LIB}
+)
+
+add_library(pjproject::pjsua STATIC IMPORTED)
+set_target_properties(pjproject::pjsua PROPERTIES
+  IMPORTED_LOCATION ${PJSUA_LIB}
+)
+
+target_include_directories(pjproject::pjsua
+  INTERFACE
+  $<BUILD_INTERFACE:${pjproject_SOURCE_DIR}/pjsip/include>
+  $<INSTALL_INTERFACE:include>
+)
+
diff --git a/core/CMakeLists.txt b/core/CMakeLists.txt
index e69de29..febd4f0 100644
--- a/core/CMakeLists.txt
+++ b/core/CMakeLists.txt
@@ -0,0 +1 @@
+add_subdirectory(src)
diff --git a/core/src/CMakeLists.txt b/core/src/CMakeLists.txt
new file mode 100644
index 0000000..7bb624f
--- /dev/null
+++ b/core/src/CMakeLists.txt
@@ -0,0 +1,13 @@
+set(CORE_SRC
+  core.c
+)
+
+list(TRANSFORM CORE_SRC PREPEND ${CMAKE_CURRENT_LIST_DIR}/)
+
+include(FetchContent)
+
+find_package(OpenSSL REQUIRED)
+
+add_library(pigeon-core ${CORE_SRC})
+target_include_directories(pigeon-core PUBLIC ${CMAKE_CURRENT_LIST_DIR}/src)
+target_link_libraries(pigeon-core OpenSSL::SSL)
diff --git a/core/src/core.c b/core/src/core.c
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/core/src/core.c
@@ -0,0 +1 @@
+
diff --git a/core/src/core.h b/core/src/core.h
new file mode 100644
index 0000000..e69de29
diff --git a/core/src/thread_util.h b/core/src/thread_util.h
new file mode 100644
index 0000000..ce88638
--- /dev/null
+++ b/core/src/thread_util.h
@@ -0,0 +1,26 @@
+#ifndef THREAD_UTIL_H
+#define THREAD_UTIL_H
+
+#include <stdint.h>
+
+// Method return count of physical cores in system
+
+#if defined(_WIN32) || defined(_WIN64)
+#include <windows.h>
+
+size_t get_core_count(void) {
+  SYSTEM_INFO sys_info;
+  GetSystemInfo(&sys_info);
+
+  return (size_t)sys_info.dwNumberOfProcessors;
+}
+#elif defined(__unix__) || defined(__unix) ||                                  \
+    (defined(__APPLE__) && defined(__MACH__))
+#include <unistd.h>
+
+size_t get_core_count(void) { return (size_t)sysconf(_SC_NPROCESSORS_ONLN); }
+#else
+#error "Get core count feature not realised for current platform."
+#endif
+
+#endif // !THREAD_UTIL_H