Real VoIP cell phone
Assume you don't want to pay for 3 years contract with any provider, can consider to have voip cell phone at low rate.
1) smartphone
1st of all you need a smartphone
Not matter Android or iPhone
2) then you need phone number
I used Rogers Pay as You Go, $100 for one year, means one year expiration, you will have one phone number, SIM card, 1st 5 min $0.25 per minute, then $0.15 per minute during the day, $0.15 for SMS, don't open voicemail box that will always charge you when there is call reach your voicemail box and listening massage.
Let's say you spend $10 per month, you only can talk 40-50 minutes or 66 SMS, not too much, right? but if this number only for emergency situation, just used to keep one phone number your friend can reach, it's not too bad since you at least know who called you if you don't take it, calling display is free and SMS most of time is enough to contact you in real time.
3) network access
Wi Fi always free for us, in the home and most of Cafe shop, university campus, community library. The second option is 3G day pass if really busy and want to talk a lot that day. Rogers 3G day pass is $2.00 for 20MB, can talk around hour, cost around $2 + 60min x $0.02 = $3.20 per day. Compared with Pay as You Go, one hour costs $15.
4) Voip client
Best choices are Skype and Fring, the luck thing is skype doesn't cost on local cell phone minutes in Canada, skypeout is $0.02 per minute, fringout is $0.008 per minute
So let's see how much will be cost using voip cell phone for 240 minutes:
1) wifi option
$10 voice/SMS(40 min or 66 SMS) + $4 skyout (200 min x $0.02) = $14
$10 voice/SMS(40 min or 66 SMS) + $2 fringout (200 min x 0.01) = $12
2) 3G day pass option
$10 voice/SMS(40 min or 66 SMS) + $2 x 3 day pass + $4 skyout (200 min x $0.02) = $20 skyout
$10 voice/SMS(40 min or 66 SMS) + $2 x 3 day pass + $2 fringout (200 min x 0.01) = $18 fringout
Note: There is not big difference for local call or long distance for voip cell phone, also it's totally free when call skype or fring contact.