Make calls from your PC

Do not mix PSTN and ADSL!

With a modem 33 or 56Kb / s, to connect, the modem dials the phone number of a subscriber to the PSTN network, just like a telephone. The recipient may be a telephone, FAX, another modem, provided that the actors (and call) speak the same language (protocol). And on the CTS, the cost will be charged to your phone ...

With an ADSL modem, you are permanently connected with your ISP, you are assigned an IP address and connect to other IP addresses on the Internet. The ADSL modem is more akin to a "network card" that a modem with respect to the connection.

With a modem RTC, for example you could connect directly to another PC (your home or house) and remote start with a simple phone call, interest standard ATX! With ADSL, known as PC is switched on and connected to the Internet (not good with all the viruses that roam!).


Anything that connects a conventional phone is the CTS network and uses the low frequency (voice), the ADSL modem connects through a filter that only passes frequencies that ADSL (and isolates equipment CTS) .

With a modem, your ISP (you have dialed the phone number) you connect to a PSTN gateway / TCPIP that lets you access the Internet, but it remains the basis of a dial-up connection!

The phone dialer for Windows allows a modem classic command asking him to make the number for you and that's all. is still RTC.


The CTS line can operate in 'voice' to call, or in 'Data' connections for modems and fax machines.
- Mode 'Data', the modem transmits fully to the data received from the PC (modulation), and conversely, data from the line to the PC (demodulation).
- Mode 'Vocal', audio signals on the PSTN (your words or the equivalent) are not interpreted by the modem, and therefore are not transmitted to the PC via the USB or serial link, and some models modems (internal cards) have input / audio outputs to relay the audio to the soundcard to use the microphone and speakers of the PC.


And know what you want to!

Telephone modem CTS

Voice Mode

You need a modem with input / output connected to the sound card (microphone and speakers connected to the PC!) Software (Winphone or others) will allow you to store numbers, numbering, send / receive Fax, etc ...
Such as a (pun intended ;-)!), You can also be called as a telephone.
Your PC has become a big phone / fax / phone book, but always by RTC, therefore invoice!

Data Mode

if the called party uses the same software that you (Winphone), digital communication is the more need for sound output on the modem or connection to the sound card software will provide the digital encoding of your voice (microphone) and return of the voice of the corresponding (by HP). Additional advantages, recording conversations, answering machine functions, etc. ... But in this mode, impossible to reach a fix!

Call from PC to PC

Whatever the modem, simply connect to the Internet, the audio is digitally encoded.
Many programs allow, Skipe, Teamspeak, Winphone, including messengers MSN, Yahoo, etc ...
Nothing to say, or the almost zero cost, since in the ADSL package!

Call with an ADSL modem from PC to phone.

Large interest, since you can reach the world through the Internet ...
Technically, no problem, you must leave the IP network in the vicinity of the person and return to the RTC, thus a gateway TCPIP / CTS (the inverse of that used with a modem) ... but Ouch! aie! problem! billing on the CTS!
Tawain if I call this method, the PTT of Taiwan will have to send me a note of the communication between the PSTN gateway TCPIP / CTS and my corresponding Taiwanese since it was the appellant who pays communication ...! !
That is the problem, a simple billing question.

However, there are regions where the phone is free (Canada, Florida and others), and in this case, the call to a phone is possible provided that the bridges are in place (but the implementation and services are not free).

There is software for calling a landline, such as Net2Phone, which offers dozens of free minutes as gifts of welcome, I've installed and tried several times to call in Canada without ever succeed in obtaining communication (although this may be due to my config, firewall or other).


Finally, while this is still a little sad ... with ADSL, and to reach a fixed or send a fax, you are forced to use a modem ...


Skype allows you to call a phone

To 0.10 Dollars / minute (less than 1 dollar / h), you can reach much here: http://www.skype.com/SkypeOut/help.globalrate.html

For billing purposes, the prepayment is therefore to provide a number of Visa card (or other ...)