Instituto Superior Técnico

Serviços de Informática


SI provides Técnico’s community with Voice over IP (VoIP) service that can be used on computers and/or smartphones.

It is due to this service that it is possible to make voice calls within Técnico’s network (free between Técnico’s network numbers and internal extensions), provided that you have a properly configured VoIP client.

SIP Addresses

VoIP on Técnico uses the Simple Initiation Protocol (SIP) to establish voice calls.

In order to make or receive a call, users must have a SIP address. These addresses are similar to e-mail addresses, so in Técnico, SIP addresses have the format (Técnico ID), where the Técnico ID is the user’s username.

Each user can consult information about the personal use of VoIP service and the history of calls made in the last year.

Click to Dial – C2D

The Click to Dial or C2D service is a VoIP subservice, which allows:

  • save phone and VoIP contacts, working just like a phone book on the web;
  • make a VoIP call, without the user dialing the number himself: C2D connects to both the sender and the receiver simultaneously, and connects the two parties to each other;
  • each user has their own phonebook.

Call Recorder

Técnico’s VoIP service allows that, in case the call recipient is not available when the call is made, the caller leaves a voice message, which will be delivered to the recipient’s mailbox, in an audio format compatible with the generality of systems.


To configure the softphone application on your computer, tablet or smartphone, you must configure the SIP account with the following generic parameters:

  • Domain:
  • User ID: (Técnico ID)
  • Password: (matching password)
  • Display Name: (A display name)
  • Authorization Name: (Técnico ID)
  • Enable Outbound Proxy Usage: Yes
  • Proxy Server Address:


In the case of users who use NAT boxes or certain firewalls, they may detect problems, which they must communicate to SI, via e-mail.

VoIP client configuration instructions:

Frequently asked questions (FAQs):