diff --git a/tunmgr/tunmgr.py b/tunmgr/tunmgr.py
index e425e76a103bdae490784fb3234abda4895b185d..1733e01498ece5ff856e4dbbbc50570921825ca4 100755
--- a/tunmgr/tunmgr.py
+++ b/tunmgr/tunmgr.py
@@ -9,7 +9,7 @@ from math import log
 
 from gsm import *
 
-SMS_SIZE = 160*14 # lettres GSM
+SMS_SIZE = 153*14 # lettres GSM
 PEER = sys.argv[1]
 PORT = 51117