Index: channels/chan_misdn.c
===================================================================
--- channels/chan_misdn.c	(revision 123644)
+++ channels/chan_misdn.c	(working copy)
@@ -2329,6 +2329,7 @@
 		ast_queue_hangup_with_cause(ast, AST_CAUSE_PROTOCOL_ERROR);
 	}
 
+	ast_channel_lock(p->ast);
 	tmp = pbx_builtin_getvar_helper(p->ast, "CRYPT_KEY");
 
 	if (!ast_strlen_zero(tmp)) {
@@ -2337,7 +2338,9 @@
 	} else {
 		chan_misdn_log(3, p->bc->port, " --> Connection is without BF encryption\n");
 	}
+	ast_channel_unlock(p->ast);
 
+	ast_channel_lock(ast);
 	tmp = pbx_builtin_getvar_helper(ast, "MISDN_DIGITAL_TRANS");
 	if (!ast_strlen_zero(tmp) && ast_true(tmp)) {
 		chan_misdn_log(1, p->bc->port, " --> Connection is transparent digital\n");
@@ -2345,6 +2348,7 @@
 		p->bc->hdlc = 0;
 		p->bc->nojitter = 1;
 	}
+	ast_channel_unlock(ast);
 
 	p->state = MISDN_CONNECTED;
 	stop_indicate(p);
@@ -2565,12 +2569,15 @@
 	bc = p->bc;
 
 	if (bc) {
-		const char *tmp=pbx_builtin_getvar_helper(ast,"MISDN_USERUSER");
+		const char *tmp;
+		ast_channel_lock(ast);
+		tmp=pbx_builtin_getvar_helper(ast,"MISDN_USERUSER");
 		if (tmp) {
 			ast_log(LOG_NOTICE, "MISDN_USERUSER: %s\n", tmp);
 			strcpy(bc->uu, tmp);
 			bc->uulen=strlen(bc->uu);
 		}
+		ast_channel_unlock(ast);
 	}
 
 	MISDN_ASTERISK_TECH_PVT(ast) = NULL;
@@ -2614,12 +2621,14 @@
 		stop_bc_tones(p);
 
 	bc->out_cause = ast->hangupcause ? ast->hangupcause : AST_CAUSE_NORMAL_CLEARING;
-		
+	
+	ast_channel_lock(ast);		
 	if ( (varcause = pbx_builtin_getvar_helper(ast, "HANGUPCAUSE")) ||
 	     (varcause = pbx_builtin_getvar_helper(ast, "PRI_CAUSE"))) {
 		int tmpcause = atoi(varcause);
 		bc->out_cause = tmpcause ? tmpcause : AST_CAUSE_NORMAL_CLEARING;
 	}
+	ast_channel_unlock(ast);
     
 	chan_misdn_log(1, bc->port, "* IND : HANGUP\tpid:%d ctx:%s dad:%s oad:%s State:%s\n", p->bc ? p->bc->pid : -1, ast->context, ast->exten, ast->cid.cid_num, misdn_get_ch_state(p));
 	chan_misdn_log(3, bc->port, " --> l3id:%x\n", p->l3id);
@@ -3875,7 +3884,10 @@
 
 void import_ch(struct ast_channel *chan, struct misdn_bchannel *bc, struct chan_list *ch)
 {
-	const char *tmp = pbx_builtin_getvar_helper(chan, "MISDN_PID");
+	const char *tmp;
+	
+	ast_channel_lock(chan);
+	tmp = pbx_builtin_getvar_helper(chan, "MISDN_PID");
 	if (tmp) {
 		ch->other_pid = atoi(tmp);
 		chan_misdn_log(3, bc->port, " --> IMPORT_PID: importing pid:%s\n", tmp);
@@ -3901,6 +3913,7 @@
 	tmp = pbx_builtin_getvar_helper(chan, "MISDN_KEYPAD");
 	if (tmp)
 		ast_copy_string(bc->keypad, tmp, sizeof(bc->keypad));
+	ast_channel_unlock(chan);
 }
 
 void export_ch(struct ast_channel *chan, struct misdn_bchannel *bc, struct chan_list *ch)