--- name: "Device::Modem::FAQ" section: "3pm" platform: "linux" package: "perl-device-modem" version: "1.59-3" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/Device::Modem::FAQ" --- # Device::Modem::FAQ(3pm) ## Device::Modem::FAQ This is a Frequently Asked Questions list about `"Device::Modem"` perl extension. ### What is "Device::Modem"? `"Device::Modem"` is a perl extension written in pure perl that allows to communicate with modems, or generically with `"AT command set compliant"` devices connected to your computer via a **serial port**. ### Who is the author of this work? Cosimo Streppone (cosimo@cpan.org), an Italian guy, who works and enjoys writing perl programs and objects. If you want to know more, go to http://www.streppone.it/cosimo/work/perl/ ### BTW, what is Perl? If you are asking that, probably you are in the wrong place. Perl is a wonderful programming language, that cuts development times, helps developer keep mental health, good life-style, doesn't pollute developer's mind, allows complete freedom of style, and (from perl manual), *gives you enough* *rope to hang yourself*. Some starting points: - • \ - Reference site for Perl programmers - • \ - Perl Mongers home - • \ - Comprehensive Perl Archive Network - • \ - Higher Perl souls - • \ - Large Perl community ### What is an "AT command set"? It is a set of standard commands, also called `"Hayes"`, in which (almost) all commands begin with `"AT"` prefix and they allow to control a modem, router, whatever device. Also cellular phones work with a subset of standard `"AT"` commands. ### What is a modem? What the heck are you doing here? http://www.google.com/search?q=Tech+glossary+modem ### What are the requisites of "Device::Modem"? You must have: - • A working computer with a standard RS-232 serial port - • An AT-compliant device (a modem will do perfectly here :-) - • A working Perl installation - • `"Device::SerialPort"` module installed if you are on some unix platform. `"Win32::SerialPort"` module installed if you are on Win32 platform. ### Is it multi-platform? `"Device::Modem"` works close to the serial port communication layer, which varies on many platforms. It relies on `"Device::SerialPort"` and `"Win32::SerialPort"` modules for all low-level communication layer. It tries to build a platform independent layer above these two low-level modules, so developers don't need to distinguish among different platforms. It's been reported to work on `"Win32"`, `"Linux"`, `"Mac OS X"`, `"FreeBSD"`, `"NetBSD"`, `"OpenBSD"`, `"ARM-Linux"` and `"Solaris"`. ### Can I use it for my commercial application? Yes, it is allowed by its license, that is the same as Perl language. If you are using it in a commercial package, or plan to do so, please inform the author (Cosimo Streppone, cosimo@cpan.org \). Thank you. ### Why the \[insert\_you\_preferred\_feature\_here\] does not work? This is an open-source software developed in my little home spare time and for my personal interest and amusement. This module has a test suite, but it is not very extensive, so it is possible that some feature X does not work, or it is not implemented yet or I cannot test it. If you are in this situation, please contact me \ and provide the following information: - • Your operating system version and architecture. Complete output of `"perl -V"` command is good for this. - • Your perl version. Again `"perl -V"`. - • Your `"Device::Modem"`, `"Device::SerialPort"` and (if you are using it) `"Device::Gsm"` version. In case of doubt, send the output of: ``` perl -MDevice::Modem -le 'print Device::Modem->VERSION' ``` Thank you. ### Do XModem transfers work? This is definitely reported to be working by several users, who also contributed patches and tested the feature. Otherwise, just look at Aaron Mitti's Device::SerialPort::Xmodem CPAN module. ### XModem sucks. What about ZModem? It might seem that XModem and ZModem should be well over dead at this point. But, looks like several old/new devices still support them. So, **ZModem** support has been contributed by a user, and will be added to the main release Soon(tm). ### Why I keep getting "can't open device: /dev/xxxxx at .../Modem.pm line 468" errors ? First of all, be sure to use **Device::Modem version 1.52+**. Probably you don't have the correct permissions to access your modem device (usually /dev/modem, or /dev/ttyS0 on unix and COM1/COM2/... on windows). Or you are trying to use the examples that come with Device::Modem distribution with an older version (Device::Modem \<= 1.33). In this case, you should upgrade to Device::Modem 1.52+. ### Why I get the error "Can't call method "purge\_all" on an undefined value at .../Modem.pm line 545" ? Again, **upgrade to Device::Modem version 1.52+**. If you get this error, it means that the communication port could not be opened. Most probably you don't have permissions to access your serial port, or you have used a wrong device name (check your device entry in `"/dev"` folder). Since version 1.52, `Device::Modem::connect()` will try to automatically reconnect if your port connection shuts down, or the `"Device::SerialPort"`, or `"Win32::SerialPort"` underlying object is deleted or invalidated. You should really upgrade to Device::Modem 1.52+. ### Can I make voice calls with this modem? **No**. What you can do, is voice call **dialing**. After the dialing though, you have to speak. Your computer can not do that, unless you have a PBX board, at least not with Device::Modem. ### This module is pretty slow. What can I do? Make sure you are using that latest version. From version 1.30, the main "send-command" / "wait-answer" cycle has been sensibly improved for speed, though you now have to specify a timeout if you want the module to wait an answer if modem is not ready. Probably this is the better compromise... ### Can I make a \[insert\_your\_preferred\_number\_here\] euro donation to you for this fantastic module? Oh, yes! Please feel free to contact cosimo@cpan.org to decide details about this... :-) ### I think you are a ?#!x$\*z!#(!\* and your software sucks Uh. Please contact me, so I can improve my software design, ideas and coding, but only if you explain the reasons of your criticism. Thank you.