diff --git a/doc/standards.txt b/doc/standards.txt
index 2b85cb04..35f2a3a2 100644
--- a/doc/standards.txt
+++ b/doc/standards.txt
@@ -166,3 +166,12 @@ Describes the general background and assumption of wireless features.
 	Capability: Network Perspective
 - S.R0006-808:	Wireless Features Description: Circuit Switched Call Precedence Over
 	CDMA Packet Data Session
+
+Common PCN Handset Specification (CPHS)
+=======================================
+
+This specification includes certain pre-standard extensions to GSM
+standards. oFono implements some of the features found in the Phase 2
+specification, version 4.2.
+
+The specification itself is not publicly available.