diff --git a/module-apps/application-call/ApplicationCall.cpp b/module-apps/application-call/ApplicationCall.cpp
index 3ec9c5199..31475266f 100644
--- a/module-apps/application-call/ApplicationCall.cpp
+++ b/module-apps/application-call/ApplicationCall.cpp
@@ -7,30 +7,32 @@
  * @details
  */
 #include "ApplicationCall.hpp"
-#include "Application.hpp"
 
-#include "MessageType.hpp"
 #include "data/CallSwitchData.hpp"
-#include "log/log.hpp"
-#include "time/time_conversion.hpp"
 #include "windows/CallMainWindow.hpp"
 #include "windows/CallWindow.hpp"
 #include "windows/EmergencyCallWindow.hpp"
 #include "windows/EnterNumberWindow.hpp"
+
+#include <Application.hpp>
+#include <MessageType.hpp>
+#include <UiCommonActions.hpp>
+
+#include <log/log.hpp>
+#include <service-cellular/ServiceCellular.hpp>
+#include <service-cellular/api/CellularServiceAPI.hpp>
+#include <service-audio/api/AudioServiceAPI.hpp>
+#include <service-appmgr/ApplicationManager.hpp>
+#include <time/time_conversion.hpp>
 #include <ticks.hpp>
 
-#include "service-cellular/ServiceCellular.hpp"
-#include "service-cellular/api/CellularServiceAPI.hpp"
-#include "service-audio/api/AudioServiceAPI.hpp"
-
-#include "service-appmgr/ApplicationManager.hpp"
 #include <cassert>
 
 namespace app
 {
 
     ApplicationCall::ApplicationCall(std::string name, std::string parent, bool startBackgound)
-        : Application(name, parent, startBackgound, 4096 + 2048),
+        : Application(name, parent, startBackgound, app::call_stack_size),
           timerCall(CreateAppTimer(1000, true, [=]() { timerCallCallback(); }))
     {}
 
@@ -199,7 +201,6 @@ namespace app
 
     void ApplicationCall::createUserInterface()
     {
-
         gui::AppWindow *window = nullptr;
 
         window = new gui::CallMainWindow(this);
@@ -215,16 +216,6 @@ namespace app
         windows.insert(std::pair<std::string, gui::AppWindow *>(window->getName(), window));
     }
 
-    void ApplicationCall::setDisplayedNumber(std::string num)
-    {
-        phoneNumber = num;
-    }
-
-    const std::string &ApplicationCall::getDisplayedNumber()
-    {
-        return phoneNumber;
-    }
-
     void ApplicationCall::runCallTimer()
     {
         callStartTime       = utils::time::Timestamp();
@@ -244,4 +235,17 @@ namespace app
     void ApplicationCall::destroyUserInterface()
     {}
 
+    void ApplicationCall::handleCallEvent(const std::string &number)
+    {
+        LOG_INFO("number: [%s]", number.c_str());
+        auto ret = CellularServiceAPI::DialNumber(this, number.c_str());
+        LOG_INFO("CALL RESULT: %s", (ret ? "OK" : "FAIL"));
+    }
+
+    void ApplicationCall::handleAddContactEvent(const std::string &number)
+    {
+        LOG_INFO("add contact information: %s", number.c_str());
+        app::contact(this, app::ContactOperation::Add, number);
+    }
+
 } // namespace app
diff --git a/module-apps/application-call/ApplicationCall.hpp b/module-apps/application-call/ApplicationCall.hpp
index 1b2f25091..909b92c6d 100644
--- a/module-apps/application-call/ApplicationCall.hpp
+++ b/module-apps/application-call/ApplicationCall.hpp
@@ -8,7 +8,9 @@
 
 namespace app
 {
-    inline const std::string name_call = "ApplicationCall";
+    inline const std::string name_call      = "ApplicationCall";
+    constexpr std::uint16_t call_stack_size = 8192;
+
     namespace window
     {
         inline const std::string name_call              = "CallWindow";
@@ -26,9 +28,8 @@ namespace app
         void RingingHandler(const CellularNotificationMessage *const msg);
 
       protected:
-        std::string phoneNumber;
         AppTimer timerCall;
-        utils::time::Timestamp callStartTime      = 0;
+        utils::time::Timestamp callStartTime = 0;
         utils::time::Duration callDuration;
         utils::time::Timestamp callDelayedStopTime = 0;
         void timerCallCallback();
@@ -53,5 +54,8 @@ namespace app
         // move to previous application
         void runCallTimer();
         void stopCallTimer();
+
+        void handleCallEvent(const std::string &number);
+        void handleAddContactEvent(const std::string &number);
     };
 } /* namespace app */
diff --git a/module-apps/application-call/windows/EnterNumberWindow.cpp b/module-apps/application-call/windows/EnterNumberWindow.cpp
index 6c8d1d1d4..b5d4c1152 100644
--- a/module-apps/application-call/windows/EnterNumberWindow.cpp
+++ b/module-apps/application-call/windows/EnterNumberWindow.cpp
@@ -11,21 +11,27 @@
 #include "../ApplicationCall.hpp"
 #include "../data/CallAppStyle.hpp"
 #include "../data/CallSwitchData.hpp"
-#include "InputMode.hpp"
-#include "UiCommonActions.hpp"
-#include "i18/i18.hpp"
-#include "service-appmgr/ApplicationManager.hpp"
-#include "service-cellular/api/CellularServiceAPI.hpp"
-#include <ContactRecord.hpp>
+
 #include <application-phonebook/windows/PhonebookContact.hpp>
+#include <ContactRecord.hpp>
+#include <i18/i18.hpp>
+#include <InputMode.hpp>
+#include <service-appmgr/ApplicationManager.hpp>
+#include <service-cellular/api/CellularServiceAPI.hpp>
+#include <UiCommonActions.hpp>
+
+#include <phonenumbers/phonenumberutil.h>
+#include <phonenumbers/asyoutypeformatter.h>
 
 namespace gui
 {
     using namespace callAppStyle;
     using namespace callAppStyle::enterNumberWindow;
 
-    EnterNumberWindow::EnterNumberWindow(app::Application *app, std::string windowName) : AppWindow(app, windowName)
+    EnterNumberWindow::EnterNumberWindow(app::Application *app, std::string windowName)
+        : AppWindow(app, windowName), numberUtil(*PhoneNumberUtil::GetInstance()), currentRegionCode(defaultRegionCode)
     {
+        switchFormatter(currentRegionCode);
         buildInterface();
     }
 
@@ -34,13 +40,6 @@ namespace gui
 
     void EnterNumberWindow::setNumberLabel(const std::string num)
     {
-        auto app = dynamic_cast<app::ApplicationCall *>(application);
-        if (app == nullptr) {
-            LOG_ERROR("app != ApplicationCall");
-            return;
-        }
-        app->setDisplayedNumber(num);
-
         numberLabel->setText(num);
 
         if (numberLabel->getText().length() == 0) {
@@ -80,8 +79,7 @@ namespace gui
     {
         auto app = dynamic_cast<app::ApplicationCall *>(application);
         if (app != nullptr) {
-            auto phoneNumber = app->getDisplayedNumber();
-            return app::contact(getApplication(), app::ContactOperation::Add, phoneNumber);
+            app->handleAddContactEvent(enteredNumber);
         }
         return false;
     }
@@ -116,62 +114,53 @@ namespace gui
         }
         auto code = translator.handle(inputEvent.key, InputMode({InputMode::phone}).get());
         if (inputEvent.state == InputEvent::State::keyReleasedShort) {
+            // Call function
             if (inputEvent.keyCode == KeyCode::KEY_LF) {
-                std::string num = app->getDisplayedNumber();
-                LOG_INFO("number: [%s]", num.c_str());
-                auto ret = CellularServiceAPI::DialNumber(application, num.c_str());
-                LOG_INFO("CALL RESULT: %s", (ret ? "OK" : "FAIL"));
+                app->handleCallEvent(enteredNumber);
                 return true;
             }
+            // Clear/back function
             else if (inputEvent.keyCode == KeyCode::KEY_RF) {
-                std::string num = app->getDisplayedNumber();
                 // if there isn't any char in phone number field return to previous application
-                if (num.empty()) {
+                if (enteredNumber.empty()) {
+                    formatter->Clear();
                     sapm::ApplicationManager::messageSwitchPreviousApplication(application);
-                    return true;
                 }
+                // if there is the last char just clear input
+                else if (enteredNumber.size() == 1) {
+                    clearInput();
+                }
+                else {
+                    // remove last digit and reformat entered number otherwise
+                    enteredNumber = enteredNumber.substr(0, enteredNumber.size() - 1);
+                    initFormatterInput(enteredNumber);
+                    setNumberLabel(formattedNumber);
 
-                num = num.substr(0, num.size() - 1);
-                setNumberLabel(num);
-
-                application->refreshWindow(RefreshModes::GUI_REFRESH_FAST);
-
+                    application->refreshWindow(RefreshModes::GUI_REFRESH_FAST);
+                }
                 return true;
             }
             else if (code != 0) {
-                std::string num = app->getDisplayedNumber();
-                num += code;
-                setNumberLabel(num);
-
-                app->refreshWindow(RefreshModes::GUI_REFRESH_FAST);
-
+                addDigit(code);
                 return true;
             }
         }
         else if (inputEvent.state == InputEvent::State::keyReleasedLong) {
             // erase all characters from phone number
             if (inputEvent.keyCode == KeyCode::KEY_RF) {
-                std::string num = app->getDisplayedNumber();
                 // if there isn't any char in phone number field return to previous application
-                if (num.empty()) {
+                if (enteredNumber.empty()) {
                     sapm::ApplicationManager::messageSwitchPreviousApplication(application);
                     return true;
                 }
 
-                setNumberLabel("");
-
-                application->refreshWindow(RefreshModes::GUI_REFRESH_FAST);
+                clearInput();
 
                 return true;
             }
             // long press of '0' key is translated to '+'
             else if (inputEvent.keyCode == KeyCode::KEY_0) {
-                std::string num = app->getDisplayedNumber();
-                num += '+';
-                setNumberLabel(num);
-
-                application->refreshWindow(RefreshModes::GUI_REFRESH_FAST);
-
+                addDigit('+');
                 return true;
             }
         }
@@ -182,6 +171,7 @@ namespace gui
 
     bool EnterNumberWindow::handleSwitchData(SwitchData *data)
     {
+        auto app = dynamic_cast<app::ApplicationCall *>(application);
 
         if (data == nullptr) {
             LOG_ERROR("Received null pointer");
@@ -190,14 +180,17 @@ namespace gui
 
         app::CallSwitchData *callData = dynamic_cast<app::CallSwitchData *>(data);
         if (callData != nullptr) {
-            std::string num = callData->getPhoneNumber();
-            setNumberLabel(num);
+            enteredNumber = callData->getPhoneNumber();
+
+            /// init formatter with provided number, set formatted number to be
+            /// displayed on the label
+            initFormatterInput(enteredNumber);
+            setNumberLabel(formattedNumber);
             application->refreshWindow(RefreshModes::GUI_REFRESH_FAST);
+
             switch (callData->getType()) {
             case app::CallSwitchData::Type::EXECUTE_CALL: {
-                LOG_INFO("number: [%s]", num.c_str());
-                auto ret = CellularServiceAPI::DialNumber(application, num.c_str());
-                LOG_INFO("CALL RESULT: %s", (ret ? "OK" : "FAIL"));
+                app->handleCallEvent(enteredNumber);
                 return true;
             }
 
@@ -219,4 +212,40 @@ namespace gui
         return false;
     }
 
+    void EnterNumberWindow::switchFormatter(const std::string &regionCode)
+    {
+        auto newFormatter = std::unique_ptr<Formatter>(numberUtil.GetAsYouTypeFormatter(regionCode));
+        formatter.swap(newFormatter);
+        LOG_INFO("Switched formatter to region: %s", regionCode.c_str());
+    }
+
+    void EnterNumberWindow::initFormatterInput(const std::string &number)
+    {
+        formatter->Clear();
+        for (auto c : number) {
+            formatter->InputDigit(c, &formattedNumber);
+        }
+    }
+
+    void EnterNumberWindow::addDigit(const std::string::value_type &digit)
+    {
+        enteredNumber += digit;
+        formatter->InputDigit(digit, &formattedNumber);
+        setNumberLabel(formattedNumber);
+        application->refreshWindow(RefreshModes::GUI_REFRESH_FAST);
+    }
+
+    const std::string &EnterNumberWindow::getEnteredNumber() const noexcept
+    {
+        return enteredNumber;
+    }
+
+    void EnterNumberWindow::clearInput()
+    {
+        enteredNumber.clear();
+        formattedNumber.clear();
+        formatter->Clear();
+        setNumberLabel("");
+        application->refreshWindow(RefreshModes::GUI_REFRESH_FAST);
+    }
 } /* namespace gui */
diff --git a/module-apps/application-call/windows/EnterNumberWindow.hpp b/module-apps/application-call/windows/EnterNumberWindow.hpp
index 09e269abc..116923e95 100644
--- a/module-apps/application-call/windows/EnterNumberWindow.hpp
+++ b/module-apps/application-call/windows/EnterNumberWindow.hpp
@@ -9,25 +9,33 @@
 #pragma once
 
 #include "../ApplicationCall.hpp"
-#include "AppWindow.hpp"
-#include "application-call/widgets/Icons.hpp"
-#include "gui/widgets/BottomBar.hpp"
-#include "gui/widgets/Image.hpp"
-#include "gui/widgets/Label.hpp"
-#include "gui/widgets/TopBar.hpp"
-#include "gui/widgets/Window.hpp"
+#include "../widgets/Icons.hpp"
+
+#include <Application.hpp>
+#include <AppWindow.hpp>
 #include <ContactRecord.hpp>
+#include <gui/input/Translator.hpp>
+#include <gui/widgets/BottomBar.hpp>
+#include <gui/widgets/Image.hpp>
+#include <gui/widgets/Label.hpp>
+#include <gui/widgets/TopBar.hpp>
+#include <gui/widgets/Window.hpp>
+
+#include <phonenumbers/phonenumberutil.h>
+#include <phonenumbers/asyoutypeformatter.h>
+
+#include <memory>
+#include <string>
 
 namespace gui
 {
-
-    /*
-     *
-     */
     class EnterNumberWindow : public AppWindow
     {
+        using PhoneNumberUtil = i18n::phonenumbers::PhoneNumberUtil;
+        using Formatter       = i18n::phonenumbers::AsYouTypeFormatter;
+
       protected:
-        gui::Label *numberLabel   = nullptr;
+        gui::Label *numberLabel             = nullptr;
         gui::AddContactIcon *newContactIcon = nullptr;
 
         void setNumberLabel(const std::string num);
@@ -39,15 +47,26 @@ namespace gui
 
         bool onInput(const InputEvent &inputEvent) override;
         bool handleSwitchData(SwitchData *data) override;
+        const std::string &getEnteredNumber() const noexcept;
 
         void rebuild() override;
         void buildInterface() override;
         void destroyInterface() override;
 
       private:
+        const std::string defaultRegionCode = "PL";
         gui::KeyInputMappedTranslation translator;
+        PhoneNumberUtil &numberUtil;
+        std::unique_ptr<Formatter> formatter;
+        std::string formattedNumber;
+        std::string enteredNumber;
+        std::string currentRegionCode;
 
         bool addNewContact();
+        void switchFormatter(const std::string &countryCode);
+        void initFormatterInput(const std::string &number);
+        void addDigit(const std::string::value_type &digit);
+        void clearInput();
     };
 
 } /* namespace gui */
diff --git a/module-sys/SystemManager/SystemManager.cpp b/module-sys/SystemManager/SystemManager.cpp
index 2ce61478e..4c06fdfb6 100644
--- a/module-sys/SystemManager/SystemManager.cpp
+++ b/module-sys/SystemManager/SystemManager.cpp
@@ -23,7 +23,7 @@ namespace sys
     const char *systemManagerServiceName = "SysMgrService";
 
     SystemManager::SystemManager(TickType_t pingInterval)
-        : Service(systemManagerServiceName), pingInterval(pingInterval)
+        : Service(systemManagerServiceName, "", 8192), pingInterval(pingInterval)
     {
         // Specify list of channels which System Manager is registered to
         busChannels = {BusChannels::SystemManagerRequests};
diff --git a/source/main.cpp b/source/main.cpp
index 91f485771..5dce4ff24 100644
--- a/source/main.cpp
+++ b/source/main.cpp
@@ -45,6 +45,9 @@
 // module-sys
 #include "SystemManager/SystemManager.hpp"
 
+// libphonenumber
+#include <phonenumbers/phonenumberutil.h>
+
 class vfs vfs;
 
 class BlinkyService : public sys::Service
@@ -154,6 +157,11 @@ int main()
     auto sysmgr = std::make_shared<sys::SystemManager>(5000);
 
     sysmgr->StartSystem([sysmgr]() -> int {
+        /// force initialization of PhonenumberUtil because of its stack usage
+        /// otherwise we would end up with an init race and PhonenumberUtil could
+        /// be initiated in a task with stack not big enough to handle it
+        i18n::phonenumbers::PhoneNumberUtil::GetInstance();
+
         vfs.Init();
 
         bool ret = false;