diff --git a/schema/pgsql/schema.sql b/schema/pgsql/schema.sql
index 0c835aaaa..8e594e01c 100644
--- a/schema/pgsql/schema.sql
+++ b/schema/pgsql/schema.sql
@@ -55,9 +55,11 @@ CREATE TABLE contact (
     username citext, -- reference to web user
     default_channel_id bigint NOT NULL REFERENCES channel(id),
     color varchar(7) NOT NULL, -- hex color codes e.g #000000
+    external_uuid uuid NOT NULL,
 
     CONSTRAINT pk_contact PRIMARY KEY (id),
-    UNIQUE (username)
+    UNIQUE (username),
+    UNIQUE (external_uuid)
 );
 
 CREATE TABLE contact_address (
@@ -74,8 +76,10 @@ CREATE TABLE contactgroup (
     id bigserial,
     name citext NOT NULL,
     color varchar(7) NOT NULL, -- hex color codes e.g #000000
+    external_uuid uuid NOT NULL,
 
-    CONSTRAINT pk_contactgroup PRIMARY KEY (id)
+    CONSTRAINT pk_contactgroup PRIMARY KEY (id),
+    UNIQUE (external_uuid)
 );
 
 CREATE TABLE contactgroup_member (
diff --git a/schema/pgsql/upgrades/029.sql b/schema/pgsql/upgrades/029.sql
new file mode 100644
index 000000000..14b362a39
--- /dev/null
+++ b/schema/pgsql/upgrades/029.sql
@@ -0,0 +1,16 @@
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+
+ALTER TABLE contact ADD COLUMN external_uuid uuid UNIQUE;
+ALTER TABLE contactgroup ADD COLUMN external_uuid uuid UNIQUE;
+
+UPDATE contact SET external_uuid = uuid_generate_v4() WHERE external_uuid IS NULL;
+UPDATE contactgroup SET external_uuid = uuid_generate_v4() WHERE external_uuid IS NULL;
+
+ALTER TABLE contact ALTER COLUMN external_uuid SET NOT NULL;
+ALTER TABLE contactgroup ALTER COLUMN external_uuid SET NOT NULL;
+
+DROP EXTENSION "uuid-ossp";
+
+
+ALTER TABLE contact DROP COLUMN external_uuid;
+ALTER TABLE contactgroup DROP COLUMN external_uuid;
\ No newline at end of file