diff --git a/common_src/lib/liblynq-at-extension/lynq_at.cpp b/common_src/lib/liblynq-at-extension/lynq_at.cpp
new file mode 100755
index 0000000..80c6588
--- /dev/null
+++ b/common_src/lib/liblynq-at-extension/lynq_at.cpp
@@ -0,0 +1,301 @@
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <string.h>
+#include <log/log.h>
+#include <pthread.h>
+#include <errno.h>
+#include "liblog/lynq_deflog.h"
+#include "include/lib_at/lynq_at.h"
+
+#define LYNQ_AT_SERVICE_PORT 8087
+#define OUT_MAX_SIZE 1024
+#define USER_LOG_TAG "LYNQ_AT"
+#define AT_EXTERSION_SOCKET_NAME "/dev/socket/lynq_atsvc_socket_1"
+#define LINE __LINE__
+#define FUNC __FUNCTION__
+static pthread_mutex_t s_startupMutex = PTHREAD_MUTEX_INITIALIZER;
+typedef enum
+{
+    A_SUCCESS = 0,
+    A_ERROR = -1
+}LYNQ_AT_E;
+
+/*lei add : maybe sento/revc error*/
+int result = A_SUCCESS;
+/*lei add : maybe sento/revc error*/
+int sockfd = 0;
+char *output = NULL;
+char buffer_at[OUT_MAX_SIZE] = {0};
+struct sockaddr_in addr_serv;
+struct sockaddr_un addr_server;
+
+
+socklen_t len;
+LYNQ_AT_CALLBACK tmp = NULL;
+bool connect_state = false;
+#define SOCKET_ZERO   0
+#define SOCKET_SUCC   1
+#define SOCKET_FAIL  -1
+
+/**
+ * @brief Catch exceptions and free malloc's memory
+ * 
+ * @param signum Type:[IN] signal
+ */
+static void signal_handler(int signum)
+{
+    switch(signum)
+    {
+         case SIGABRT:
+            LYDBGLOG("recv SIGABRT\n");
+            break;
+         case SIGBUS:
+            LYDBGLOG("recv SIGBUS\n");
+            break;
+         case SIGFPE:
+            LYDBGLOG("recv SIGFPE\n");
+            break;
+         case SIGILL:
+            LYDBGLOG("recv SIGILL\n");
+            break;
+         case SIGSEGV:
+            LYDBGLOG("recv SIGSEGV\n");
+            break;
+         default:
+            LYDBGLOG("recv unknown signal\n");
+            break;
+    }
+    if(NULL != output)
+    {
+        free(output);
+        output = NULL;
+    }
+}
+
+
+int socket_local_client (char* name) {
+    //struct sockaddr_un server;
+    //int fd = 0;
+    LYINFLOG("[%d][%s] enter",LINE,FUNC);
+    sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (sockfd < 0)
+    {
+        LYDBGLOG("Can't open stream socket (%s)", name);
+        return -1;
+    }
+    addr_server.sun_family = AF_UNIX;
+    memset(addr_server.sun_path, '\0', sizeof(addr_server.sun_path));
+    strncpy(addr_server.sun_path, name, sizeof(addr_server.sun_path) - 1);
+    if (connect(sockfd, (struct sockaddr *) &addr_server, sizeof(struct sockaddr_un)) < 0)
+    {
+        close(sockfd);
+        LYDBGLOG("Can't connect to server side, path: %s, %s", name, strerror(errno));
+        return -1;
+    }
+    LYINFLOG("[%d][%s] connect %s success",LINE,FUNC,name);
+    return sockfd;
+}
+bool send_msg_to_service(int fd,char *msg,int size)
+{
+    LYDBGLOG("[%d][%s] enter",LINE,FUNC);
+    if (fd < 0)
+    {
+        LYDBGLOG("fd invalid when send to atci service. errno = %d", errno);
+        return false;
+    }
+    if(NULL == msg)
+    {
+        LYDBGLOG("atcmd is null.");
+        return false;
+    }
+    int sendLen = send(fd, msg, size, 0);
+    if (sendLen != size)
+    {
+        LYDBGLOG("lose data when send to atci service. errno = %d", errno);
+        return false;
+    }
+    LYDBGLOG("client send to app demo: %s", msg);
+    return true;
+}
+
+int atsvc_cmd_recv(int fd, char *buf, int len)
+{
+    LYINFLOG("[%d][%s] enter",LINE,FUNC);
+    int ret = 0;
+    // fd_set rfds;
+    // //FD_CLR(fd, &rfds);
+    // FD_SET(fd, &rfds);
+    // ret = select(fd + 1, &rfds, NULL, NULL, NULL);
+    // if (ret <= 0)
+    // {
+    //     LYDBGLOG("acti_cmd_recv client select error, ret=%d, error=%s(%d),fd=%d", ret,strerror(errno), errno, fd);
+    //     return SOCKET_FAIL;
+    // }
+    // if (FD_ISSET(fd, &rfds))
+    // {
+        LYDBGLOG("[%d][%s] recv before",LINE,FUNC);
+        ret = recv(fd, buf, len, 0);
+        LYDBGLOG("[%d][%s] recv after",LINE,FUNC);
+        if (ret < 0)
+        {
+            LYDBGLOG("acti_cmd_recv client select error, ret=%d, error=%s(%d),fd=%d", ret,strerror(errno), errno, fd);
+            return SOCKET_FAIL;
+        }
+        else if(ret == 0)
+        {
+            LYDBGLOG("acti_cmd_recv client recv error, ret=%d, error=%s(%d),fd=%d", ret,strerror(errno), errno, fd);
+            return SOCKET_ZERO;
+    }
+    // else
+    // {
+    //   //buf[ret] = '\0';
+    // }
+//   }
+  return SOCKET_SUCC;
+}
+/**
+ * @brief send third cmd to service and receive input,then send output to service
+ * 
+ * @param parm 
+ * @return void* 
+ */
+void *thread_recv(void *parm)
+{
+    //signal(SIGPIPE, signal_handler);
+    //signal(SIGABRT, signal_handler);
+    //signal(SIGBUS, signal_handler);
+    //signal(SIGFPE, signal_handler);
+    //signal(SIGILL, signal_handler);
+    //signal(SIGSEGV, signal_handler);
+    LYINFLOG("[%d][%s] enter",LINE,FUNC);
+    int recv = 0;
+    int send = 0;
+    char at_cmd[100] = {0};
+    int fd = -1;
+    int ret = 0;
+    fd = socket_local_client(AT_EXTERSION_SOCKET_NAME);
+    if(fd <= 0)
+    {
+        LYDBGLOG("socket_local_client  fail\n");
+        connect_state = false;
+        pthread_mutex_unlock(&s_startupMutex);
+        return NULL;
+    }
+    int len_buf = strlen(buffer_at);
+    if(!send_msg_to_service(fd,buffer_at,len_buf))
+    {
+        LYDBGLOG("send_msg_to_service  fail\n");
+        connect_state = false;
+        pthread_mutex_unlock(&s_startupMutex);
+        return NULL;
+    }
+    connect_state = true;
+    pthread_mutex_unlock(&s_startupMutex);
+    char *input = NULL;
+    output = (char *)malloc(sizeof(char)*OUT_MAX_SIZE);
+    if(NULL == output)
+    {
+        LYDBGLOG("thread_recv malloc fail\n");
+        return NULL;
+    }
+    TryNewLink:
+    if(connect_state == false)
+    {
+        if (connect(fd, (struct sockaddr *) &addr_server, sizeof(struct sockaddr_un)) < 0)
+        {
+            close(fd);
+            LYDBGLOG("Can't connect to server side, path: %s, errno:%d", AT_EXTERSION_SOCKET_NAME, errno);
+            return NULL;
+        }
+        connect_state = true;
+    }
+    while (1)
+    {
+        /*receive at cmd*/
+        memset(at_cmd, 0, sizeof(at_cmd));
+        ret = atsvc_cmd_recv(fd, at_cmd,sizeof(at_cmd));
+        if (ret < 0)
+        {
+            LYDBGLOG("[%d][%s]receive CMD error",LINE,FUNC);
+            continue;
+        }
+        else if(ret == SOCKET_ZERO)
+        {
+            ALOGE("maybe client socket closed 1. retry new link!");
+            connect_state = false;
+            goto TryNewLink;
+        }
+        input = at_cmd;
+        //begin deal with callback
+        tmp(input, output, OUT_MAX_SIZE);
+        LYDBGLOG("lynq_reg_third_at send output to service\n");
+        if(!send_msg_to_service(fd,output, strlen(output)))
+        {
+            LYDBGLOG("thread_recv send fail\n");
+            continue;
+        }
+    }
+    free(output);
+    output = NULL;
+    if(fd != 0)
+    {
+        close(fd);
+    }
+    return NULL;
+}
+
+/**
+ * @brief Threads are created to communicate with the server
+ * 
+ * @return int 
+ */
+int lynq_connect_service_start(void)
+{
+    LYINFLOG("[%d][%s] enter",LINE,FUNC);
+    pthread_t lynq_at_tid = -1;
+    int rt = pthread_create(&lynq_at_tid, NULL, thread_recv, NULL);
+    pthread_mutex_lock(&s_startupMutex);
+    LYINFLOG("[%d][%s] pthread mutex unlock",LINE,FUNC);
+    LYINFLOG(",rt:%d,connect state:%d\n",rt,connect_state);
+    if((connect_state != true) && rt < 0)
+    {
+        LYERRLOG("connect fail,rt:%d,connect state:%d\n",rt,connect_state);
+        return -1;
+    }
+    return 0;
+}
+
+/**
+ * @brief Type:[IN] send third at cmd to service
+ * @param ext_at Type:[IN] input at cmd
+ * @param callback Type:[IN]
+ * @return int 
+ */
+int lynq_reg_third_at(const char *ext_at, LYNQ_AT_CALLBACK callback)
+{
+    if(NULL == ext_at || NULL == callback)
+    {
+        return A_ERROR;
+    }
+    memcpy(buffer_at, ext_at, strlen(ext_at));
+    tmp = callback;
+    LYLOGSET(LOG_DEBUG);
+    LYLOGEINIT(USER_LOG_TAG);
+    LYDBGLOG("lynq_reg_third_at start\n");
+    int ret = lynq_connect_service_start();
+    
+    if(ret != 0)
+    {
+        LYDBGLOG("lynq_connect_service_start start failed\n");
+        return A_ERROR;
+    }
+    LYDBGLOG("lynq_connect_service_start success ret:%d\n",ret);
+    return A_SUCCESS;
+}
+