(http://www.faximum.com/technotes/222)
TITLE: #222 - Configuring data/fax sharing KEYWORDS: fax line, modem, faxgetty, uucplock file, data/fax sharing RELEASE: All CLASSIFICATION: All PROBLEM: Customer wishes to configure a fax modem for shared fax and data use. CAUSE: N/A SOLUTION: One of the features of the Faximum fax server software is the ability to share a single phone line and modem with both data and fax traffic. As outlined below, this is a far more complex undertaking than might first appear and requires the careful cooperation between different components of your UNIX or Linux system. Note also that the data/fax sharing features of Faximum have only be tested to date on SCO OpenServer although the code is common across all platforms and ought to work in a similar manner. Faximum Technical Support would be pleased to assist any customers who have purchased technical support and who experience difficulty configuring and using data/fax sharing. Note that data/fax sharing is not part of the Faximum ELS product. ELS customers wishing to utilise the data/fax feature will have to upgrade to Faximum PLUS. Before continuing it is necessary to determine which type of data/fax sharing you wish to configure: Data In + Fax In Data In + Fax In/Out Data Out + Fax Out Data Out + Fax In/Out Data In/Out + Fax In/Out Before configuring your system for data/fax sharing it is STRONGLY recommended that you configure and test fax-only operation. That is, make sure that the fax in and/or out functions work properly before proceeding to configure data/fax sharing. If there are problems the fax operation of your server they are much easier to diagnose without the complication of data/fax sharing. Similarly, if problems arise with data/fax sharing, knowing that fax-only operations were working prior to configuring data/fax sharing makes determine the cause of the problem much easier. A. Background and Theory of Operation -------------------------------------- In order to understand some of the configuration issues (and, more importantly, some of the causes of possible problems) it is helpful to understand the issues surrounding data/fax sharing. Briefly put, there are three problems that must be addressed: 1) how to ensure that the data application(s) and fax server do not simultaneously attempt to use the modem; 2) how to determine if an incoming call is a fax or data call (if both are to be handled); and 3) how to properly initialise the modem so that an outgoing data call is not made when the modem has been left in fax mode (resulting in the incorrect modulation and calling tones being used). A.1 - The first issue is addressed by using lock files. Whenever an application is using the modem it creates a lock file in a known location that other applications can check for before trying to use the modem. In order to properly configure the Faximum fax software to respect the lock file protocol it is necessary to determine the name of the lock file used by your system for the port in question. On most systems these lock files will be located in one of the following directories: RedHat Linux /var/lock SCO OpenServer /var/spool/locks Sun Solaris /var/spool/locks HP-UX 1x.x /var/spool/locks SCO OpenServer /var/spool/locks The file will start with the characters "LCK." and be followed by something that is specific to the port being locked. The best way to determine the name of this file is to run your data application (be it a uucp or cu outbound data call or an incoming login call) and monitor the contents of the appropriate lock directory to see the name of the lock file. A.2 - The second issue is handled by the modem which must be capable of operating in "adaptive answer" mode. When a data/fax modem is in adaptive answer mode and handles an incoming call it will determine if the call is a fax or data call and pass that information to faxgetty so that it can be handled appropriately. Faximum has only tested the MT-1932 and MT-2834 modems to verify that they operate properly in adaptive answer mode. Faximum cannot commit to the proper operation of data/fax sharing with other modems. A.3 - The third issue is usually handled automatically by the fax server software which resets the modem after every call as well as the modem which will normally reset to data mode when the DTR signal is dropped. B. Configuring Data/Fax Sharing -------------------------------- Most of the configuration changes need to be made to the fax line configuration file for the lines you wish to operate in data/fax sharing mode. The location of these files (which are normally named fax-line-1, fax-line-2, etc.) depends on the product: Faximum Client/Server /opt/FAXserver/dev/ Faximum ELS or PLUS /opt/faximum/dev/ Faximum FMS /var/faximum/dev/ Please locate the appropriate fax line configuration file(s) for your system before proceeding. B.1 - Lock Files As described in section A.1 above it is necessary to determine the name of the lock file used by your system to lock the serial communication port. Once you have determined the name of the lock file then you need to edit (or add) the uucp-lock-file parameter in the fax line configuration file. For example, on Faximum PLUS the file is /opt/faximum/dev/fax-line-1 and the parameter might look like: uucp-lock-file = /var/spool/uucp/LCK..tty1a B.2 - Data/Fax Sharing Mode If you want to handle both data and fax incoming calls then it will be necessary to enable "adaptive answer" as discussed in section A.2 above. To do this add the following parameter to the fax line configuration file: data-receive = yes If your inbound traffic will be fax only (i.e. no inbound data calls) then do not set "data-receive". If your inbound traffic will be data only (i.e. no inbound fax calls) then do not set "data-receive". Also, instead of enabling faxgetty in the inittab (see TechNote 211 for more information), you will need to enable the normal getty process for your version of UNIX or Linux to enable login prompts to appear when you dial up the modem in data mode. If you find that the standard getty is interfering with outbound fax calls you may need to use uugetty or the "-r" flag to getty. Please consult the documentation for your system or (if you have purchased technical support) contact Faximum Technical Support for assistance and guidance. TechNote: 222 - Copyright 2001 Faximum Software Inc., All Rights Reserved. Last Updated: Mon Jun 11 12:47:15 PDT 2001 The complete set of Faximum TechNotes are available on the Internet at http://www.faximum.com/support© Copyright 2001 Faximum Software Inc. All Rights Reserved.