diff --git a/TODO b/TODO
index 5589bb1b..f963954d 100644
--- a/TODO
+++ b/TODO
@@ -285,6 +285,12 @@ Voicecall
   Complexity: C1
   Owner: Pekka Pessi <pekka.pessi@nokia.com>
 
+- Long phone numbers. According to 3GPP TS 24.008, the callee address
+  can be up to 80 digits long.
+
+  Priority: Medium
+  Complexity: C2
+
 - Dial strings. Include CLIR prefixes and 2nd stage dial strings in the
   DialString call property. Add dialstring accessor method to C API.