diff --git a/code/application/source/sf_app/code/source/4gMng/sf_eg91_sim.c b/code/application/source/sf_app/code/source/4gMng/sf_eg91_sim.c
index 06b8c4f7c..98242d149 100755
--- a/code/application/source/sf_app/code/source/4gMng/sf_eg91_sim.c
+++ b/code/application/source/sf_app/code/source/4gMng/sf_eg91_sim.c
@@ -2419,7 +2419,9 @@ SINT32 sf_module_complete_init(void)
                     ttyRet = sf_hal_ttyusb2_write(gsmPara, strlen(gsmPara));
                     SF_CHECK_RETURN(ttyRet, SF_GPRS_MODULE_ERROR_WRITE);
                     callTime = 0;
+                    ttyData.cmp = "OK";
                     ttyData.len = 255;//Must wait for OK or error.
+                    sf_sleep_ms(50);
                 }
                 else if(strstr((const char *)gsmPara, "CME ERROR: SIM not inserted"))
                 {
@@ -2437,7 +2439,7 @@ SINT32 sf_module_complete_init(void)
                     ttyRet = sf_hal_ttyusb2_write(gsmPara, strlen(gsmPara));
                     //printf("ttyRet:%d\n", ttyRet);
                     SF_CHECK_RETURN(ttyRet, SF_GPRS_MODULE_ERROR_WRITE);
-                    //ttyData.cmp = "ATE1";
+                    ttyData.cmp = "OK";
                     ttyData.len = 255;//Must wait for OK or error.
                 }
 
@@ -2499,7 +2501,15 @@ SINT32 sf_module_complete_init(void)
                 else
                 {
                     callTime++;
-
+                    if(callTime%2)
+                    {
+                        strcpy(gsmPara, "AT+GSN\r");
+                        ttyRet = sf_hal_ttyusb2_write(gsmPara, strlen(gsmPara));
+                        SF_CHECK_RETURN(ttyRet, SF_GPRS_MODULE_ERROR_WRITE);
+                        ttyData.cmp = "OK";
+                        ttyData.len = 255;//Must wait for OK or error.
+                        sf_sleep_ms(50);
+                    }
                     if(callTime > 10)
                     {
                         ret = SF_SIM_ERROR_AT_TIMEOUT;