diff --git a/res/res_fax.c b/res/res_fax.c
index 5d666085f4..c926d95dbb 100644
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -74,6 +74,9 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 					<option name="f">
 						<para>Allow audio fallback FAX transfer on T.38 capable channels.</para>
 					</option>
+					<option name="n">
+						<para>Disable usage of T.38 on otherwise T.38 capable channels.</para>
+					</option>
 					<option name="s">
 						<para>Send progress Manager events (overrides statusevents setting in res_fax.conf).</para>
 					</option>
@@ -107,6 +110,9 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 					<option name="f">
 						<para>Allow audio fallback FAX transfer on T.38 capable channels.</para>
 					</option>
+					<option name="n">
+						<para>Disable usage of T.38 on otherwise T.38 capable channels.</para>
+					</option>
 					<option name="s">
 						<para>Send progress Manager events (overrides statusevents setting in res_fax.conf).</para>
 					</option>
@@ -267,6 +273,7 @@ enum {
 	OPT_STATUS      = (1 << 3),
 	OPT_ALLOWAUDIO  = (1 << 5),
 	OPT_REQUEST_T38 = (1 << 6),
+	OPT_DISABLE_T38 = (1 << 7),
 };
 
 AST_APP_OPTIONS(fax_exec_options, BEGIN_OPTIONS
@@ -274,6 +281,7 @@ AST_APP_OPTIONS(fax_exec_options, BEGIN_OPTIONS
 	AST_APP_OPTION('c', OPT_CALLERMODE),
 	AST_APP_OPTION('d', OPT_DEBUG),
 	AST_APP_OPTION('f', OPT_ALLOWAUDIO),
+	AST_APP_OPTION('n', OPT_DISABLE_T38),
 	AST_APP_OPTION('s', OPT_STATUS),
 	AST_APP_OPTION('z', OPT_REQUEST_T38),
 END_OPTIONS);
@@ -1619,7 +1627,8 @@ static int receivefax_exec(struct ast_channel *chan, const char *data)
 	}
 
 	if ((ast_channel_get_t38_state(chan) == T38_STATE_UNAVAILABLE) ||
-	    ast_test_flag(&opts, OPT_ALLOWAUDIO)) {
+	    ast_test_flag(&opts, OPT_ALLOWAUDIO) ||
+	    ast_test_flag(&opts, OPT_DISABLE_T38)) {
 		details->option.allow_audio = AST_FAX_OPTFLAG_TRUE;
 	}
 
@@ -1644,17 +1653,19 @@ static int receivefax_exec(struct ast_channel *chan, const char *data)
 		}
 	}
 
-	if (set_fax_t38_caps(chan, details)) {
-		ast_string_field_set(details, error, "T38_NEG_ERROR");
-		ast_string_field_set(details, resultstr, "error negotiating T.38");
-		set_channel_variables(chan, details);
-		fax_session_release(s, token);
-		ao2_ref(s, -1);
-		ao2_ref(details, -1);
-		return -1;
+	if (!ast_test_flag(&opts, OPT_DISABLE_T38)) {
+		if (set_fax_t38_caps(chan, details)) {
+			ast_string_field_set(details, error, "T38_NEG_ERROR");
+			ast_string_field_set(details, resultstr, "error negotiating T.38");
+			set_channel_variables(chan, details);
+			fax_session_release(s, token);
+			ao2_ref(s, -1);
+			ao2_ref(details, -1);
+			return -1;
+		}
 	}
 
-	if (details->caps & AST_FAX_TECH_T38) {
+	if (!ast_test_flag(&opts, OPT_DISABLE_T38) && (details->caps & AST_FAX_TECH_T38)) {
 		if (receivefax_t38_init(chan, details)) {
 			ast_string_field_set(details, error, "T38_NEG_ERROR");
 			ast_string_field_set(details, resultstr, "error negotiating T.38");
@@ -2094,7 +2105,8 @@ static int sendfax_exec(struct ast_channel *chan, const char *data)
 	}
 
 	if ((ast_channel_get_t38_state(chan) == T38_STATE_UNAVAILABLE) ||
-	    ast_test_flag(&opts, OPT_ALLOWAUDIO)) {
+	    ast_test_flag(&opts, OPT_ALLOWAUDIO) ||
+	    ast_test_flag(&opts, OPT_DISABLE_T38)) {
 		details->option.allow_audio = AST_FAX_OPTFLAG_TRUE;
 	}
 
@@ -2123,17 +2135,19 @@ static int sendfax_exec(struct ast_channel *chan, const char *data)
 		}
 	}
 
-	if (set_fax_t38_caps(chan, details)) {
-		ast_string_field_set(details, error, "T38_NEG_ERROR");
-		ast_string_field_set(details, resultstr, "error negotiating T.38");
-		set_channel_variables(chan, details);
-		fax_session_release(s, token);
-		ao2_ref(s, -1);
-		ao2_ref(details, -1);
-		return -1;
+	if (!ast_test_flag(&opts, OPT_DISABLE_T38)) {
+		if (set_fax_t38_caps(chan, details)) {
+			ast_string_field_set(details, error, "T38_NEG_ERROR");
+			ast_string_field_set(details, resultstr, "error negotiating T.38");
+			set_channel_variables(chan, details);
+			fax_session_release(s, token);
+			ao2_ref(s, -1);
+			ao2_ref(details, -1);
+			return -1;
+		}
 	}
 
-	if (details->caps & AST_FAX_TECH_T38) {
+	if (!ast_test_flag(&opts, OPT_DISABLE_T38) && (details->caps & AST_FAX_TECH_T38)) {
 		if (sendfax_t38_init(chan, details)) {
 			ast_string_field_set(details, error, "T38_NEG_ERROR");
 			ast_string_field_set(details, resultstr, "error negotiating T.38");