diff --git a/lib/include/srslte/asn1/liblte_mme.h b/lib/include/srslte/asn1/liblte_mme.h
index 78e2cae69..85b8b2241 100644
--- a/lib/include/srslte/asn1/liblte_mme.h
+++ b/lib/include/srslte/asn1/liblte_mme.h
@@ -175,6 +175,7 @@ typedef struct{
     uint8 imsi[15];
     uint8 imei[15];
     uint8 imeisv[16];
+    uint32 tmsi;
 }LIBLTE_MME_MOBILE_ID_STRUCT;
 // Functions
 LIBLTE_ERROR_ENUM liblte_mme_pack_mobile_id_ie(LIBLTE_MME_MOBILE_ID_STRUCT  *mobile_id,
diff --git a/lib/src/asn1/liblte_mme.cc b/lib/src/asn1/liblte_mme.cc
index ea7729519..da79fb791 100644
--- a/lib/src/asn1/liblte_mme.cc
+++ b/lib/src/asn1/liblte_mme.cc
@@ -297,6 +297,7 @@ LIBLTE_ERROR_ENUM liblte_mme_pack_mobile_id_ie(LIBLTE_MME_MOBILE_ID_STRUCT  *mob
 {
     LIBLTE_ERROR_ENUM  err = LIBLTE_ERROR_INVALID_INPUTS;
     uint8             *id;
+    uint32             id32;
     uint32             i;
     uint8              length;
     bool               odd = false;
@@ -317,6 +318,11 @@ LIBLTE_ERROR_ENUM liblte_mme_pack_mobile_id_ie(LIBLTE_MME_MOBILE_ID_STRUCT  *mob
             id  = mobile_id->imeisv;
             length = 9;
             odd = false;
+        }else if(LIBLTE_MME_MOBILE_ID_TYPE_TMSI == mobile_id->type_of_id){
+            id32 = mobile_id->tmsi;
+            length = 4;
+            odd = false;
+        }
         }else{
             // FIXME: Not handling these IDs
             return(err);
@@ -325,30 +331,48 @@ LIBLTE_ERROR_ENUM liblte_mme_pack_mobile_id_ie(LIBLTE_MME_MOBILE_ID_STRUCT  *mob
         // Length
         **ie_ptr = length;
         *ie_ptr += 1;
-
-        // | Identity digit 1 | odd/even | Id type |
-        if(odd)
+        if(LIBLTE_MME_MOBILE_ID_TYPE_TMSI != mobile_id->type_of_id)
         {
-          **ie_ptr  = (id[0] << 4) | (1 << 3) | mobile_id->type_of_id;
-        }else{
-          **ie_ptr  = (id[0] << 4) | (0 << 3) | mobile_id->type_of_id;
-        }
-        *ie_ptr  += 1;
+            // | Identity digit 1 | odd/even | Id type |
+            if(odd)
+            {
+                **ie_ptr  = (id[0] << 4) | (1 << 3) | mobile_id->type_of_id;
+            }else{
+                **ie_ptr  = (id[0] << 4) | (0 << 3) | mobile_id->type_of_id;
+            }
+            *ie_ptr  += 1;
 
-        // | Identity digit p+1 | Identity digit p |
-        for(i=0; i<7; i++)
-        {
-            (*ie_ptr)[i] = (id[i*2+2] << 4) | id[i*2+1];
-        }
-        *ie_ptr += 7;
-        if(!odd)
-        {
-          **ie_ptr = 0xF0 | id[15];
-          *ie_ptr += 1;
+        
+            // | Identity digit p+1 | Identity digit p |
+            for(i=0; i<7; i++)
+            {
+                (*ie_ptr)[i] = (id[i*2+2] << 4) | id[i*2+1];
+            }
+            *ie_ptr += 7;
+            if(!odd)
+            {
+              **ie_ptr = 0xF0 | id[15];
+              *ie_ptr += 1;
+            }
+
+            err = LIBLTE_SUCCESS;
         }
+        else{
 
-        err = LIBLTE_SUCCESS;
-    }
+          **ie_ptr  = (0xFF << 4) | (0 << 3) | mobile_id->type_of_id;
+          *ie_ptr  += 1;
+          //4-Byte based ids
+          **ie_ptr  = (id32 >> 24) & 0xFF;
+          *ie_ptr  += 1;
+          **ie_ptr  = (id32 >> 16) & 0xFF;
+          *ie_ptr  += 1;
+          **ie_ptr  = (id32 >> 8) & 0xFF;
+          *ie_ptr  += 1;
+          **ie_ptr  = id32 & 0xFF;
+          *ie_ptr  += 1;
+
+          err = LIBLTE_SUCCESS;
+        }
 
     return(err);
 }
diff --git a/srsepc/src/mme/s1ap_nas_transport.cc b/srsepc/src/mme/s1ap_nas_transport.cc
index b5c2b8531..736eb4d3d 100644
--- a/srsepc/src/mme/s1ap_nas_transport.cc
+++ b/srsepc/src/mme/s1ap_nas_transport.cc
@@ -1542,8 +1542,9 @@ s1ap_nas_transport::pack_attach_accept(ue_emm_ctx_t *ue_emm_ctx, ue_ecm_ctx_t *u
   }
 
   //Attach accept
-  attach_accept.eps_attach_result = LIBLTE_MME_EPS_ATTACH_RESULT_EPS_ONLY;
-  //attach_accept.eps_attach_result = LIBLTE_MME_EPS_ATTACH_RESULT_COMBINED_EPS_IMSI_ATTACH;
+  //attach_accept.eps_attach_result = LIBLTE_MME_EPS_ATTACH_RESULT_EPS_ONLY;
+  attach_accept.eps_attach_result = LIBLTE_MME_EPS_ATTACH_RESULT_COMBINED_EPS_IMSI_ATTACH;
+
   //Mandatory
   //FIXME: Set t3412 from config
   attach_accept.t3412.unit = LIBLTE_MME_GPRS_TIMER_UNIT_1_MINUTE;   // GPRS 1 minute unit
@@ -1570,13 +1571,22 @@ s1ap_nas_transport::pack_attach_accept(ue_emm_ctx_t *ue_emm_ctx, ue_ecm_ctx_t *u
                     attach_accept.guti.guti.m_tmsi);
 
   //Set EMM cause to no CS available
-  //attach_accept.emm_cause_present=false;
-  attach_accept.emm_cause_present=true;
-  attach_accept.emm_cause=18;
+  attach_accept.emm_cause_present=false;
+  //attach_accept.emm_cause_present=true;
+  //attach_accept.emm_cause=18;
+
+  //Set up LAI for combined EPS/IMSI attach
+  //attach_accept.lai_present=false;
+  attach_accept.lai_present=true;
+  attach_accept.lai.mcc = mcc;
+  attach_accept.lai.mnc = mnc;
+  attach_accept.lai.lac = 001;
+
+  attach_accept.ms_id_present=true;
+  attach_accept.ms_id.type_of_id = LIBLTE_MME_MOBILE_ID_TYPE_TMSI;
+  attach_accept.ms_id.tmsi = attach_accept.guti.guti.m_tmsi;
 
   //Make sure all unused options are set to false
-  attach_accept.lai_present=false;
-  attach_accept.ms_id_present=false;
   attach_accept.t3402_present=false;
   attach_accept.t3423_present=false;
   attach_accept.equivalent_plmns_present=false;