Now this is the first in a series I plan to do on what you can use your Mobile Broadband for. This one is all about VoIP, which is Voice over Internet Protocol. Which basically means making telephone calls over the internet. Some of the advantages of VoIP is cheaper rates on calls particularly when calling internationally. Most (all?) of the time calls to other users of the service are free and this includes to any destination in the world, and calls to other numbers are generally a lot cheaper than other telephone services. You just need to keep an eye on your data usage if you've got a limited allowance.
Now, when using VoIP on mobile networks you need to make sure you have good coverage and that your network has good Uplink (how fast it sends data) speeds as well as Downlink (how fast it receives). When I've tried to use VoIP with my network, I've always had problems with my voice sounding very choppy to them, but I can hear them fine. This is due to the data being sent a lot slower than it receives. This is standard on most (all?) consumer internet connection as consumers tend to download a lot more than they upload. (It's been a few months since I last tried this so the service on my network may have improved.)
Ok, now that you have your connection all checked out you need to decide on a VoIP provider. I would say the most popular provider at the moment is probably Skype.
Now one thing you need to bear in mind with Skype is that it is a closed network. This means you can only call other Skype customer, and only other Skype customers can call you. Unless you opt for the SkypeIn service which gives you a telephone number for your VoIP service. But this isn't generally a problem as possibly most people are Skype customers that have VoIP service. Another great advantage to Skype is that if you have your Mobile Broadband through 3 you get Skype access free of charge, so no charges for Skype-to-Skype calls on the 3 network. You can get this offer on both contract and Pay as you Go. On Pay as you Go you just need to top-up and you free Skype for 30 days, just top-up again within that 30 days and the free Skype continues. Three also offer a specialised SkypePhone. Also, in order to make calls to non-Skype customers you will need to add their SkypeOut service, which just works like a Pay as you Go phone, top it up and use the credit until it runs out, and top up again.
Now the other main service available is SIP compliant VoIP. This is a open system. Meaning that anyone with SIP service can call anyone else with SIP service regardless of who their supplier is. And as most VoIP-to-VoIP calls are free of charge you can do this from and to any SIP compliant service. As with Skype a lot of these services offer 'real world' telephone numbers you can be called on, and a service to allow you to call 'real world' numbers. By real world I mean not VoIP.