--- asterisk-11.19.0.o/res/res_fax.c	2015-08-07 18:42:14.000000000 +0200
+++ asterisk-11.19.0/res/res_fax.c	2015-12-08 19:20:16.137717563 +0200
@@ -278,12 +278,12 @@ struct fax_detect {
 	int timeout;
 	/*! \brief DSP Processor */
 	struct ast_dsp *dsp;
-	/*! \brief original audio formats */
-	struct ast_format orig_format;
 	/*! \brief fax session details */
 	struct ast_fax_session_details *details;
 	/*! \brief mode */
 	int flags;
+	/*! \brief translator path for transcoding to slinear */
+	struct ast_trans_pvt* trans;
 };
 
 /*! \brief FAX Detect flags */
@@ -3256,6 +3256,7 @@ static struct fax_detect *fax_detect_new
 
 	faxdetect->flags = flags;
 
+	faxdetect->timeout = timeout;
 	if (timeout) {
 		faxdetect->timeout_start = ast_tvnow();
 	} else {
@@ -3275,6 +3276,8 @@ static struct fax_detect *fax_detect_new
 		faxdetect->dsp = NULL;
 	}
 
+	faxdetect->trans = NULL;
+
 	return faxdetect;
 }
 
@@ -3283,6 +3286,9 @@ static struct fax_detect *fax_detect_new
 static void fax_detect_framehook_destroy(void *data) {
 	struct fax_detect *faxdetect = data;
 
+	if (faxdetect->trans)
+		ast_translator_free_path(faxdetect->trans);
+
 	ao2_ref(faxdetect, -1);
 }
 
@@ -3301,34 +3307,19 @@ static struct ast_frame *fax_detect_fram
 	struct fax_detect *faxdetect = data;
 	struct ast_fax_session_details *details;
 	struct ast_control_t38_parameters *control_params;
-	struct ast_channel *peer;
+	//struct ast_channel *peer;
+	struct ast_format slin;
+	struct ast_frame *o;
 	int result = 0;
 
+	o = NULL;
 	details = faxdetect->details;
 
+	ast_debug(5, "fax_detect_framehook called with event %d.\n", event);
+
 	switch (event) {
 	case AST_FRAMEHOOK_EVENT_ATTACHED:
-		/* Setup format for DSP on ATTACH*/
-		ast_format_copy(&faxdetect->orig_format, ast_channel_readformat(chan));
-		switch (ast_channel_readformat(chan)->id) {
-			case AST_FORMAT_SLINEAR:
-			case AST_FORMAT_ALAW:
-			case AST_FORMAT_ULAW:
-				break;
-			default:
-				if (ast_set_read_format_by_id(chan, AST_FORMAT_SLINEAR)) {
-					ast_framehook_detach(chan, details->faxdetect_id);
-					details->faxdetect_id = -1;
-					return f;
-				}
-		}
-		return NULL;
 	case AST_FRAMEHOOK_EVENT_DETACHED:
-		/* restore audio formats when we are detached */
-		ast_set_read_format(chan, &faxdetect->orig_format);
-		if ((peer = ast_bridged_channel(chan))) {
-			ast_channel_make_compatible(chan, peer);
-		}
 		return NULL;
 	case AST_FRAMEHOOK_EVENT_READ:
 		if (f) {
@@ -3344,6 +3335,7 @@ static struct ast_frame *fax_detect_fram
 
 	if ((!ast_tvzero(faxdetect->timeout_start) &&
 	    (ast_tvdiff_ms(ast_tvnow(), faxdetect->timeout_start) > faxdetect->timeout))) {
+		ast_debug(5, "fax_detect_framehook detaching due to timeout (timeout=%d, timeout_start=%ld.%06lu, elapse=%" PRId64 ".\n", faxdetect->timeout, faxdetect->timeout_start.tv_sec, faxdetect->timeout_start.tv_usec, ast_tvdiff_ms(ast_tvnow(), faxdetect->timeout_start));
 		ast_framehook_detach(chan, details->faxdetect_id);
 		details->faxdetect_id = -1;
 		return f;
@@ -3363,8 +3355,23 @@ static struct ast_frame *fax_detect_fram
 			case AST_FORMAT_ULAW:
 				break;
 			default:
+				if (!faxdetect->trans) {
+					ast_debug(5, "Attempt to process %s frame in CNG fax detection.\n", ast_getformatname(&f->subclass.format));
+					ast_format_set(&slin, AST_FORMAT_SLINEAR, 0);
+					faxdetect->trans = ast_translator_build_path(&slin, &f->subclass.format);
+				}
+				if (!faxdetect->trans) {
+					ast_debug(5, "Unable to build translation path to slinear.\n");
 				return f;
 		}
+				o = f;
+				f = ast_translate(faxdetect->trans, f, 0);
+				if (!f) {
+					ast_debug(5, "Transcoding failed.\n");
+					return o;
+				}
+				break;
+		}
 		break;
 	case AST_FRAME_CONTROL:
 		if ((f->subclass.integer == AST_CONTROL_T38_PARAMETERS) &&
@@ -3408,8 +3415,8 @@ static struct ast_frame *fax_detect_fram
 				if (ast_async_goto(chan, target_context, "fax", 1)) {
 					ast_log(LOG_NOTICE, "Failed to async goto '%s' into fax of '%s'\n", ast_channel_name(chan), target_context);
 				}
-				ast_frfree(f);
-				f = &ast_null_frame;
+				ast_frfree(o);
+				o = &ast_null_frame;
 			} else {
 				ast_channel_lock(chan);
 				ast_log(LOG_NOTICE, "FAX %s detected but no fax extension in context (%s)\n",
@@ -3420,7 +3427,8 @@ static struct ast_frame *fax_detect_fram
 		details->faxdetect_id = -1;
 	}
 
-	return f;
+	ast_frfree(f);
+	return o;
 }
 
 /*! \brief Attach a faxdetect framehook object to a channel.