diff --git a/module-bsp/board/linux/cellular/linux_cellular.cpp b/module-bsp/board/linux/cellular/linux_cellular.cpp
index 5da7b360a..8bfc1efa8 100644
--- a/module-bsp/board/linux/cellular/linux_cellular.cpp
+++ b/module-bsp/board/linux/cellular/linux_cellular.cpp
@@ -100,6 +100,9 @@ namespace bsp {
         if ((ret == -1) && (errno == EINTR)) {
             goto retry;
         }
+        else if(errno){
+            LOG_DEBUG("Read errno: %s",strerror(errno));
+        }
         return ret;
     }
 
diff --git a/module-cellular/Modem/ATParser.cpp b/module-cellular/Modem/ATParser.cpp
index 58d6cabc3..51ac4adf3 100644
--- a/module-cellular/Modem/ATParser.cpp
+++ b/module-cellular/Modem/ATParser.cpp
@@ -13,6 +13,7 @@
 #include "bsp/cellular/bsp_cellular.hpp"
 #include "ticks.hpp"
 #include "InOutSerialWorker.hpp"
+#include "MuxDaemon.hpp"
 
 std::optional<std::unique_ptr<ATParser>>
 ATParser::Create(MuxDaemon *mux, InOutSerialWorker *inOutSerial, bsp::Cellular *cellular) {
@@ -25,10 +26,61 @@ ATParser::Create(MuxDaemon *mux, InOutSerialWorker *inOutSerial, bsp::Cellular *
     }
 }
 
-ATParser::ATParser(MuxDaemon *mux, InOutSerialWorker *inOutSerial, bsp::Cellular *cellular) : mux(mux),inOutSerialWorker(inOutSerial),cellular(cellular) {
+ATParser::ATParser(MuxDaemon *mux, InOutSerialWorker *inOutSerial, bsp::Cellular *cellular) : mux(mux),
+                                                                                              inOutSerialWorker(
+                                                                                                      inOutSerial),
+                                                                                              cellular(cellular) {
     isInitialized = true;
 }
 
+std::vector<ATParser::Urc> ATParser::ParseURC() {
+
+    std::vector<ATParser::Urc> resp;
+    size_t maxPos = 0;
+
+    cpp_freertos::LockGuard lock(mutex);
+
+
+    auto pos = responseBuffer.find("RDY");
+    if (pos != std::string::npos) {
+        resp.push_back(ATParser::Urc::MeInitializationSuccessful);
+        maxPos = std::max(pos + strlen("RDY"), maxPos);
+    }
+
+    pos = responseBuffer.find("+CFUN: 1");
+    if (pos != std::string::npos) {
+        resp.push_back(ATParser::Urc::FullFuncionalityAvailable);
+        maxPos = std::max(pos + strlen("+CFUN: 1"), maxPos);
+    }
+    pos = responseBuffer.find("+CPIN: READY");
+    if (pos != std::string::npos) {
+        resp.push_back(ATParser::Urc::SimCardReady);
+        maxPos = std::max(pos + strlen("+CPIN: READY"), maxPos);
+    }
+
+    pos = responseBuffer.find("+QIND: SMS DONE");
+    if (pos != std::string::npos) {
+        resp.push_back(ATParser::Urc::SMSInitializationComplete);
+        maxPos = std::max(pos + strlen("+QIND: SMS DONE"), maxPos);
+    }
+
+    pos = responseBuffer.find("+QIND: PB DONE");
+    if (pos != std::string::npos) {
+        resp.push_back(ATParser::Urc::PhonebookInitializationComplete);
+        maxPos = std::max(pos + strlen("+QIND: PB DONE"), maxPos);
+    }
+
+    // manage string buffer
+    if(responseBuffer.size() >= maxPos){
+        responseBuffer.erase();
+    }
+    else{
+        responseBuffer = responseBuffer.substr(maxPos);
+    }
+
+    return resp;
+}
+
 int ATParser::ProcessNewData() {
     char rawBuffer[256] = {0};
 
@@ -41,8 +93,17 @@ int ATParser::ProcessNewData() {
     }
         // Received response data without active request, drop it
     else {
-        responseBuffer.erase();
-        LOG_INFO("Received unneeded data");
+        urcs = ParseURC();
+        // GSM modem is considered as fully operational when it outputs URCs specified below:
+        // 1) RDY
+        // 2) +CFUN: 1
+        // 3) +CPIN: READY
+        // 4) +QIND: SMS DONE
+        // 5) +QIND: PB DONE
+        if(urcs.size() == 5){
+            mux->StartMultiplexer();
+        }
+
     }
     return 1;
 }
@@ -79,13 +140,12 @@ std::vector<std::string> ATParser::SendCommand(const char *cmd, size_t rxCount,
         if (tokens.size() < rxCount) {
             goto wait_for_data;
         }
-        blockedTaskHandle = nullptr;
-        return tokens;
-    } else {
-        //timeout
-        blockedTaskHandle = nullptr;
-        return tokens;
+
     }
+
+    blockedTaskHandle = nullptr;
+    responseBuffer.erase(); // TODO:M.P is it okay to flush buffer here ?
+    return tokens;
 }
 
 std::vector<std::string> ATParser::Tokenizer(std::string &input, uint32_t maxTokenCount,
diff --git a/module-cellular/Modem/ATParser.hpp b/module-cellular/Modem/ATParser.hpp
index a21dbaf62..3d9bfeba3 100644
--- a/module-cellular/Modem/ATParser.hpp
+++ b/module-cellular/Modem/ATParser.hpp
@@ -31,6 +31,16 @@ class InOutSerialWorker;
 
 class ATParser {
 public:
+
+    enum class Urc{
+        MeInitializationSuccessful,
+        FullFuncionalityAvailable,
+        SimCardReady,
+        SMSInitializationComplete,
+        PhonebookInitializationComplete
+
+    };
+
     static std::optional<std::unique_ptr<ATParser>> Create(MuxDaemon* mux,InOutSerialWorker* inOutSerial,bsp::Cellular* cellular);
 
     ATParser(MuxDaemon* mux,InOutSerialWorker* inOutSerial,bsp::Cellular* cellular);
@@ -43,6 +53,8 @@ public:
 
 private:
 
+    std::vector<Urc> ParseURC();
+
     MuxDaemon* mux = nullptr;
     InOutSerialWorker* inOutSerialWorker = nullptr;
     bsp::Cellular* cellular = nullptr;
@@ -52,6 +64,8 @@ private:
     TaskHandle_t blockedTaskHandle = nullptr;
     cpp_freertos::MutexStandard mutex;
 
+    std::vector<ATParser::Urc> urcs;
+
     bool isInitialized = false;
 
 
diff --git a/module-cellular/Modem/InOutSerialWorker.cpp b/module-cellular/Modem/InOutSerialWorker.cpp
index bbd665793..06281b330 100644
--- a/module-cellular/Modem/InOutSerialWorker.cpp
+++ b/module-cellular/Modem/InOutSerialWorker.cpp
@@ -71,7 +71,10 @@ void workerTaskFunction(void *ptr) {
     InOutSerialWorker *inst = reinterpret_cast<InOutSerialWorker *>(ptr);
 
     while (1) {
-        inst->cellular->Wait(UINT32_MAX);
+        auto ret = inst->cellular->Wait(UINT32_MAX);
+        if(ret == 0){
+            continue;
+        }
 
         // AT mode is used only during initialization phase
         if (inst->mode == InOutSerialWorker::Mode::AT) {
diff --git a/module-cellular/Modem/MuxDaemon.cpp b/module-cellular/Modem/MuxDaemon.cpp
index abc357c72..00c4aecf6 100644
--- a/module-cellular/Modem/MuxDaemon.cpp
+++ b/module-cellular/Modem/MuxDaemon.cpp
@@ -83,7 +83,7 @@ MuxDaemon::MuxDaemon(NotificationMuxChannel::NotificationCallback_t callback) :
 }
 
 MuxDaemon::~MuxDaemon() {
-    CloseMux();
+    CloseMultiplexer();
 }
 
 std::unique_ptr<MuxDaemon> MuxDaemon::Create(NotificationMuxChannel::NotificationCallback_t callback) {
@@ -127,39 +127,32 @@ bool MuxDaemon::Start() {
         inOutSerialDataWorker->SendFrame(0, closeChannelCmd, sizeof(closeChannelCmd),
                                          static_cast<unsigned char>(MuxDefines::GSM0710_TYPE_UIH));
 
-        vTaskDelay(500); // give modem some time to establish mux
-
         // Try sending AT command once again
         ret = inOutSerialDataWorker->SendATCommand("AT\r",2, 500);
         if(ret.size() == 1 || ret.size() == 2){
             // Modem can send echo response or not, in either case it means that modem is operating in AT mode
-
+            return StartMultiplexer();
         }
         else{
             LOG_INFO("Starting power up procedure...");
             // If no response, power up modem and try again
             //TODO:M.P implement it cellular->PowerUp();
-            uint32_t retries = 20;
-            while (--retries) {
-                ret = inOutSerialDataWorker->SendATCommand("AT\r", 500);
-                if ( ret.size() == 2) {
-                    break;
-                }
-            }
-
-            if (retries == 0) {
-                LOG_FATAL("No communication with GSM modem");
-                return -1;
-            }
-
         }
     }
+    else if ((ret.size() == 1 && ret[0] == "OK\r\n") || (ret.size() == 2 && ret[0] == "AT\r\n" && ret[1] == "OK\r\n")){
+        return StartMultiplexer();
+    }
+
+}
+
+bool MuxDaemon::StartMultiplexer() {
+
+    // Factory reset
+    inOutSerialDataWorker->SendATCommand("AT&F\r", 1);
 
     // Turn off local echo
     inOutSerialDataWorker->SendATCommand("ATE0\r", 2);
 
-    // Factory reset
-    inOutSerialDataWorker->SendATCommand("AT&F\r", 1);
 
     // Set up modem configuration
     if (hardwareControlFlowEnable) {
@@ -225,7 +218,7 @@ bool MuxDaemon::Start() {
 }
 
 
-int MuxDaemon::CloseMux() {
+int MuxDaemon::CloseMultiplexer() {
 
     // Virtual channels need to be deinitialized in reversed order i.e control channel should be closed at the end
     for (auto w = channels.size(); --w;) {
diff --git a/module-cellular/Modem/MuxDaemon.hpp b/module-cellular/Modem/MuxDaemon.hpp
index dc84c647c..a229df216 100644
--- a/module-cellular/Modem/MuxDaemon.hpp
+++ b/module-cellular/Modem/MuxDaemon.hpp
@@ -38,6 +38,7 @@ public:
      * Multiplexer states
      */
     enum class States {
+        MUX_STATE_POWERUP,
         MUX_STATE_OPENING,
         MUX_STATE_INITILIZING,
         MUX_STATE_MUXING,
@@ -62,6 +63,8 @@ public:
     void RemoveMuxChannel(MuxChannel::MuxChannelType chan);
 
 
+    bool StartMultiplexer();
+
     int uihPfBitReceived = 0;
 
 private:
@@ -70,7 +73,7 @@ private:
 
     bool Start();
 
-    int CloseMux();
+    int CloseMultiplexer();
 
 
     constexpr static unsigned char closeChannelCmd[] = {