Can I make skype calls on iphone 3g?

I want to buy one for my family so they can call me and talk on skype, it's no problem if I can't see them, it's important they can see me. The thing is that I want them to use internet from the sim card not a Wi-Fi connnection, they need to use the internet of their mobile provider. At last how many mb will they consume if they talk with me let's say an hour, an estimate, if you can't it's alright, answer the first part of the question.

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  • Why can I not hear when I make phone calls on my iphone 4s? Whenever I try to phone people, I can't hear either them speaking or the dialing then beeping. It has worked in the past and I have not changed my settings, but the last call which I could hear I listened using my headphones.
  • Iphone 4 dropped and now i can't make calls what can i do? I dropped my iphone and the back broke but everything else is working fine excepts when i make phone calls the iphone automaticly gets in speaker but i hear anything and none can hear me what can i do?
  • Iphone 4, can't make calls out.eh Ok so I just bought a new iphone and I set everything up, but trying to ring O2 (my network), I couldnt contact them, as soon as I ring, It says calling, and immediately, call ended. It does the same with every number, so I'm wondering is there a fix… Its literally 3 hours old: S I have restarted the phone. I have full bars network, and everything else works a dream. Any help please, would be pretty good.thanks BTW, i can receive calls perfectly?