How do you make voice calls on your PC to another PC or Landline International?

Preferably not skype as it's a propriatory protocol and imo has little future in the market place because most of the big names are getting behind SIP.

http://www.call1899.co.uk/voip.php ALOT cheaper than skype and alot better as it uses SIP. (although the site is down atm but be patient)

Then get a free UK geographical number from

use https://www.sipgate.co.uk

May also think about investing in a sipphone

Get one from sipgate. Depending on the phone you get you may need a router but you don't need a router to use the software obviously.

Read about SIP here https://www.sipphone.com

I read a lot of the computer business press, and the general opinion is that Skype is excellent and has really changed the VOIP (voice over ip) market at an early stage in its life.
Skype is certainly much easier to setup and use IMHO.

There is no harm trying Skype and Sip, I have tried both, and at the moment, Skype suits me best.

Sorry try this

http://www.phonegaim.com/ (sorry if the text is squashed up in exporer they need to sort this out tbh, I'll send them an email) And be aware it's still BETA software so might not function properly.

It's the phone version of gaim, basically a gaim version with SIP support as far as I'm aware but don't quote me on that as I don't use it myself.
http://gaim.sourceforge.net



Gaim is a multiprotocol messaging client and can be downloaded here

All free software under the GPL licence, projects which recieve alot of their funding from http://www.linspire.com

For information on what SIP is, read this site.
http://www.sipcenter.com/

Note: dial 00 +44 before you dial any UK numbers and 00 before any PSTN numbers. SIpphone give you 5 free minutes of calls a day and, five calls a mintue each. Be warned SIP is still in its infancy tbh so go easy on it for the time being it will get alot better.

SIP is a request-response protocol that closely resembles two other Internet protocols, HTTP and SMTP (the protocols that power the world wide web and email); consequently, SIP sits comfortably alongside Internet applications. Using SIP, telephony becomes another web application and integrates easily into other Internet services. SIP is a simple toolkit that service providers can use to build converged voice and multimedia services.

http://www.sipcenter.com/sip.nsf/html/What+Is+SIP+Introduction

I'm sure you can all appreciate why getting behind SIP is so important.

To answer your question about dialup you can still use SIP on dialup which should now be obvious given the information in the link above. All you have to do is adjust the settings of the software you're using by changing from high to low bandwidth usage

The vast majority of people who use skype find it very good. pc-to-pc wise skype better than others as simpler and more people on it. This SIP thing may have limited lifespan as telco's are looking to migrate their entire telephony network from PSTN, POTS and PBX all old-skool analogue stuff to VOIP. Examples of this are NTL and BT. For the moment use Skype then change in future as you see fit.