DELRINA 895 Don Mills Road 6830 Via Del Oro 500-2 Park Centre Suite 240 Toronto, Ontario San Jose, California Canada M3C 1W3 U.S.A. 95119-1353 Product Support Numbers BBS:(416)441-2752 WinFax PRO 3.0 Only:(416)441-0921 Fax Back:(416)443-1614 All Other Products:(416)441-1026 Fax:(416)441-0774 ====================================================================== T E C H N I C A L N O T E S Product: WinFax PRO 3.0, WinFax PRO 2.0, WinFax LITE, WinFax 2.0 Document No.: 2008 Document Date: February 4, 1993 ====================================================================== Subject: Standards Supported by WinFax-- Class 1, Class 2, CAS and SendFax Fax standards are set down, in part, by the Telecommunications Industry Association (TIA) and jointly by Intel and Spectrafax. Additionally, Sierra Semiconductors has designed a chip set and an associated protocol for fax transmission. CCITT T.4 is the standard image format for Group 3 facsimile transmission, as specified by the Consultative Committee of International Telegraph and Telephone (CCITT). Class 1 ------- Class 1, TR-29 EIA PN2188, is a fax standard for the transmission of CCITT T.4 compressed images. With Class 1, the computer creates and interprets the images, and handles the communications session. The fax/modem only handles the transmission and reception of the data. Class 2 ------- Class 2, TR-29 EIA PN2388, is a fax standard for the transmission of CCITT T.4 images. With Class 2, the fax/modem handles both the communications session, and the transmission and reception of data. The computer creates and interprets the images. CAS (Communicating Applications Specifications) ----------------------------------------------- CAS is a standard developed by Intel and Spectrafax. The CAS standard allows for the management of facsimile transmission, reception, call logging, and phonebook maintenance. The CAS standard is a high-level programming interface designed to give programmers the means of easily adding fax communications into their programs. Sierra SendFax -------------- Sierra Semiconductor has designed a chip set for the transmission of CCITT T.4 images using a proprietary modem control protocol. This chip set allows modem manufacturers to create an inexpensive send-only fax device capable of managing a CCITT T.4 session to send an image supplied by the host computer. Standards Supported By WinFax ----------------------------- WinFax supports the two TIA standards, Class 1 and Class 2. WinFax also supports the CAS standard. Note: The CAS standard has not been closely adhered to by all fax/modem manufacturers, and unless the CAS standard--as implemented in the Intel Connection Co-Processor or Intel SatisFAXtion board--has been followed, WinFax will not be able to communicate with the CAS hardware. The final standard WinFax supports is not an industry standard, but rather a particular manufacturer's chip set. The Sierra SendFax, at one time a very popular chip set for the construction of fax/modems, is becoming less common as the cost of Class 1 and Class 2 boards decrease. WinFax also supports a variation on Class 2 developed by Touch Base Systems, called WorldPort (now owned by U.S. Robotics). This particular board is not fully Class 2 compatible. When WinFax is installed as a WorldPort, it is installed without the DOS TSR portion, and the fax device line in the WIN.INI file is changed to compensate for the different characteristics the WorldPort has. The only shortcoming of this type of fax/modem with WinFax is the inability to use the WinFax DOS TSR. Advantages of the Various Standards =================================== Class 1 and Class 2 ------------------- The fax application, in this case WinFax, directly accesses Class 1 and Class 2 boards. The Class 1 standard relies on the computer to do both data handling and communications session management; the Class 2 standard has the fax/modem hardware deal with the actual communications session, and only requires the computer to manage image file creation and interpretation. Because of this, on systems with low resources, a Class 2 fax/modem is less likely to have difficulties. Class 1 and Class 2 boards communicate with WinFax through communications ports. Because the Windows communications drivers and the system's COM ports perform the communications between the computer and the fax/modem, timing problems and conflicts can occur. SendFax ------- SendFax modems, other than not being able to receive, operate much the same as Class 2 boards. CAS --- The CAS standard in itself holds little advantage over Class 1 and Class 2 standards. CAS does, however, have a hardware advantage regarding WinFax. First, the Intel Connection Co-Processor and Intel SatisFAXtion boards, being the most common boards supported by WinFax CAS, have microprocessors that allow for a reduction in the overhead placed on the host computer. This, of course, means better over--all Windows performance while a fax is being sent or received. Second, CAS uses a hardware driver and a TSR so fax applications can communicate with the hardware and maintain the CAS board's transaction logs and phonebooks. Because the driver ultimately controls the hardware, there is little risk of hardware incompatibility. Moreover, because WinFax is installed over top of a current installation of fax software, it is unlikely the fax/modem will not work in its current configuration. This does, however, mean no other software can access the CAS driver at the same time as WinFax or a conflict will occur. The WinFax Administrator does not need to be loaded to send or receive a fax. A disadvantage associated with the driver and TSR files is that they will consume some conventional memory and possibly conflict with other programs on your system. Related Documents: 2010 Fax/Modems, Determining Compatibility with WinFax 2014 Tested and Approved Fax/Modems (WinFax PRO 3.0)