I've been happily using Blyk for a while now; the network that gives you 217 texts and 43 minutes for FREE each month without ever having to top up.
The catch is you have to have an MMS enabled phone and receive advertisements a few times a day via SMS.
Obviously those who have older mobiles and don't see the need to upgrade to a MMS phone appear outta luck.
There's an easy solution. Simply place your Blyk SIM inside a friends MMS phone. You should receive a test message from Blyk that displays in MMS form, you can also force settings to be sent by texting "SETTINGS" to 247. You don't have to accept any of them - you're only interested in getting the SIM activated.
Once your SIM has been activated (once you've received the green Blyk image) give another phone a call to ensure it's all working. Now simply place the SIM back in your old non-MMS phone and enjoy your free txts/minutes without the catch!
If you do not wish Blyk to know you're using an incompatible handset simply set your handset to not sent SIM messages without confirmation from you (easy to do on Nokias). If you don't do this you'll get an automated message from Blyk saying "Your phone is incompatible, go to Blyk.co.uk to see a list of phones, etc, etc." though your free txts/minutes will continue as usual.
Hope this is of use to some people out there!