+ String getContactName(String number);
+
+ void setContactName(String number, String name);
+
+ List<byte[]> getGroupIds();
+
+ String getGroupName(byte[] groupId);
+
+ List<String> getGroupMembers(byte[] groupId);
+
+ byte[] updateGroup(byte[] groupId, String name, List<String> members, String avatar) throws IOException, EncapsulatedExceptions, GroupNotFoundException, AttachmentInvalidException;
+
+ boolean isRegistered();
+