LINPHONE 'S USER MANUAL
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# 3. Making a call

## 3.1. Basic principles

Linphone uses the Session Initiation Protocol to establish the connection with a remote host. In this protocol each caller or callee is identified by a SIP url: sip:user_name@host_name. A sip url is very closed in syntax to an email address, excepted the “sip:“ prefix.

User_name is like a login name on an Unix machine, and host_name is the name or the IP address of the machine the user can be joined.

Note that Sip is a new telecommunication protocol designed to be simple, and it is not compatible with H323 at all.

## 3.2. Application: two users connected to the internet by a modem

Here is a "simple" way to proceed. The network requirements are :

- a 28k or more modem.

Scenario:

- Bob has to call Tom at 21:00. At 21:00 Tom connects to the internet using kppp, or gppp, or wvdial, (or other).

- Once it is connected to the internet, he can run linphone.By opening the statistics box of kppp or gppp, he can see its IP address (if not type /sbin/ifconfig to see it). The name of the modem interface should be ppp0.

- Then he sends an e-mail to Bob where it tells "My IP address is xxx.xxx.xxx.xxx.".

- Bob receives the e-mail, and then types in linphone window the name and ip address of the person he wants to contact: Tom @ xxx.xxx.xxx.xxx(Tom's IP address), and finaly press the call button.

- Then linphone rings at Tom's house while Bob can hear the ringback sound that informs him that linphone is ringing remotely. Then Tom has just to answer the call by clicking on the answer button, and then should talk each other.

If you encounter problems, see section 8-problems.

## 3.3. test trial: you have no friends to call at the moment (because it is too late for example), but would like to know if linphone really works

Since version 0.3.0, linphone comes with a test program called 'sipomatic'. Sipomatic can answer automatically to calls from linphone. To do this:

- run sipomatic from a terminal. Dont't be surprised, sipomatic does not have a graphical interface, but you don't have to interact with it.

- Then type the following sip url in the main window of linphone: sip:robot@127.0.0.1:5064 . 127.0.0.1 is a local address for your computer, and robot is the name to use for calling sipomatic. 5064 is the port where sipomatic can be joined. Normally you should always use 5060 (i.e the default port when no port is specified) to call somebody, but sipomatic is the exception: it runs on port 5064. The reason for this is that linphone already runs on 5060, and you cannot have two applications running on the same port, in the same time and on the same machine.

- Then press the call button. After one second, sipomatic should answer to your call and you should hear a short annoncement.

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