diff --git a/ngcp/avp.lua b/ngcp/avp.lua
index 55e6ca5..94cfe3e 100644
--- a/ngcp/avp.lua
+++ b/ngcp/avp.lua
@@ -24,15 +24,18 @@ NGCPAvp_MT = {
         function t.all()
             return sr.pv.get("$(avp(" .. id .. ")[*])")
         end
+        NGCPAvp_MT.__tostring = function(t)
+            local value = sr.pv.get(t.id)
+            return string.format("%s:%s", t.id, tostring(value))
+        end
         return setmetatable( t, NGCPAvp_MT )
     end
 
     function NGCPAvp:log(level)
-        local value = sr.pv.get(self.id)
         if not level then
             level = "dbg"
         end
-        sr.log(level, string.format("%s:%s\n", self.id, tostring(value)))
+        sr.log(level, tostring(self))
     end
 
     function NGCPAvp:clean()
diff --git a/ngcp/ngcp.lua b/ngcp/ngcp.lua
index 3a2d5fd..df4213e 100644
--- a/ngcp/ngcp.lua
+++ b/ngcp/ngcp.lua
@@ -368,32 +368,43 @@ end
         end
     end
 
-    function NGCP:_log_var(level, vtype, group)
+    function NGCP:_str_var(vtype, group)
         local _, v, var, vars_index, avp
+        local output = "{"
         vars_index = vtype .. "_" .. group .. "_load"
         if self.vars[vars_index] then
             for _,v in pairs(self.vars[vars_index]) do
                 for _,var in pairs(v) do
                     avp = NGCPAvp:new(var[1])
-                    avp:log(level)
+                    output = output .. tostring(avp) .. ","
                 end
             end
         end
+        output = output .. "}\n"
+        return output
     end
 
     function NGCP:log_var(level, vtype, group)
+        local vtypes, groups
+        local _,vt,gr
+
         if not level then
             level = "dbg"
         end
         if not vtype then
-            if group then
-                self:_log_var(level, "caller", group)
-                self:_log_var(level, "callee", group)
-            else
-                self:_log_var(level, "caller", "peer")
-                self:_log_var(level, "callee", "peer")
-                self:_log_var(level, "caller", "usr")
-                self:_log_var(level, "callee", "usr")
+            vtypes = {"caller", "callee"}
+        else
+            vtypes = { vtype }
+        end
+        if not group then
+            groups = { "peer", "usr"}
+        else
+            groups = { group }
+        end
+
+        for _,vt in pairs(vtypes) do
+            for _,gr in pairs(groups) do
+                sr.log(level, self:_str_var(vt, gr))
             end
         end
     end
diff --git a/tests/ngcp.lua b/tests/ngcp.lua
index ee4d7c0..a328931 100644
--- a/tests/ngcp.lua
+++ b/tests/ngcp.lua
@@ -543,5 +543,10 @@ TestNGCP = {} --class
         self.ngcp:log_var(nil, nil, "peer")
         self.ngcp:log_var("info", "caller")
     end
+
+    function TestNGCP:test_str_var()
+        self:test_caller_usr_load()
+        assertEquals(self.ngcp:_str_var("caller", "usr"), "{$avp(s:allowed_ips_grp):nil,$avp(s:man_allowed_ips_grp):nil,$avp(s:ignore_allowed_ips):nil,$avp(s:caller_account_id):2,$avp(s:caller_cc):43,$avp(s:caller_ac):1,$avp(s:caller_emergency_cli):nil,$avp(s:caller_emergency_prefix):nil,$avp(s:caller_emergency_suffix):nil,$avp(s:caller_lock):nil,$avp(s:caller_block_override):nil,$avp(s:caller_adm_block_override):nil,$avp(s:caller_allowed_clis):nil,$avp(s:caller_user_cli):nil,$avp(s:caller_block_out_mode):nil,$avp(s:caller_block_out_list):nil,$avp(s:caller_adm_block_out_mode):nil,$avp(s:caller_adm_block_out_list):nil,$avp(s:caller_peer_auth_user):nil,$avp(s:caller_peer_auth_pass):nil,$avp(s:caller_peer_auth_realm):nil,$avp(s:caller_ext_subscriber_id):nil,$avp(s:caller_ext_contract_id):nil,$avp(s:caller_prepaid):nil,$avp(s:caller_ring_group_dest):nil,$avp(s:caller_ring_group_policy):nil,$avp(s:caller_no_nat_sipping):nil,$avp(s:caller_reject_emergency):nil,$avp(s:caller_ncos_id):nil,$avp(s:caller_inbound_upn):from_user,$avp(s:caller_extension_in_npn):nil,$avp(s:caller_inbound_uprn):npn,$avp(s:caller_ipv46_for_rtpproxy):nil,$avp(s:caller_force_outbound_calls_to_peer):nil,$avp(s:caller_use_rtpproxy):nil,$avp(s:rewrite_caller_in_dpid):nil,$avp(s:rewrite_callee_in_dpid):nil,$avp(s:caller_ip_header):P-NGCP-Src-Ip,$avp(s:caller_allow_out_foreign_domain):nil,$avp(s:caller_concurrent_max):nil,$avp(s:caller_concurrent_max_out):nil,$avp(s:caller_concurrent_max_per_account):nil,$avp(s:caller_concurrent_max_out_per_account):nil,$avp(s:caller_sst_enable):no,$avp(s:caller_sst_expires):300,$avp(s:caller_sst_min_timer):90,$avp(s:caller_sst_max_timer):7200,$avp(s:caller_sst_refresh_method):UPDATE_FALLBACK_INVITE,$avp(s:caller_cloud_pbx):nil,}\n")
+    end
 -- class TestNGCP
 --EOF
\ No newline at end of file
diff --git a/tests/ngcp_avp.lua b/tests/ngcp_avp.lua
index 8b86b38..2ba70f7 100644
--- a/tests/ngcp_avp.lua
+++ b/tests/ngcp_avp.lua
@@ -57,5 +57,12 @@ TestNGCPAvp = {} --class
     function TestNGCPAvp:test_log()
         self.avp:log()
     end
+
+    function TestNGCPAvp:test_tostring()
+        self.avp(1)
+        assertEquals(tostring(self.avp), "$avp(s:testid):1")
+        self.avp("hola")
+        assertEquals(tostring(self.avp), "$avp(s:testid):hola")
+    end
 -- class TestNGCPAvp
 --EOF
\ No newline at end of file