Well. If PhoneBook is more or less standart then SMS is not standart and is absolutely ipossible on Smartphones (except you write application which will run on smartphone and communicate with PC to send SMS). However, WCL supports SMS (see GSMModemClient) over AT commands what can be used with any simple phone (except Android/BlackBerry/iPhone/WinPhone/WinMobile/Symbian)
With regards PBAP. We will think what we can do with that.