Missing part of fix of the #135 bug
diff --git a/python/receiver/gsm_input.py b/python/receiver/gsm_input.py
index 2de2f03..97ab633 100644
--- a/python/receiver/gsm_input.py
+++ b/python/receiver/gsm_input.py
@@ -38,10 +38,7 @@
         ##################################################
         # Blocks
         ##################################################
-        if version(gr.version()) >= version('3.7.9'):
-            self.message_port_register_hier_in("ppm_in")
-        else:
-            self.message_port_register_hier_out("ppm_in")
+        self.message_port_register_hier_in("ppm_in")
 
         self.low_pass_filter_0_0 = filter.fir_filter_ccf(1, firdes.low_pass(
         	1, samp_rate_out, 125e3, 5e3, firdes.WIN_HAMMING, 6.76))