Though not a special promotion, CallWithUs.com is a small but exceptionally inexpensive and very good quality BYOD (Bring Your Own Device) pay-as-you-go VoIP provider. They charge no setup, monthly, connection, or hidden fees. You pay only for the calls you make at the stated per-minute rates, and nothing more. Rates are quoted to the thousandth of a cent, and to some countries the rates are less than half of what Vonage or MagicJack charges. Example: Cameroon Land Line - CallWithUs: $0.10825 Vonage: $0.27 MagicJack: $0.26 Rebtel: $0.155 ($0.139 to 2 major cities) Google Voice: $0.18. I have not found better international rates other than where Rebtel's free calling is applicable.
Their web portal allows you to configure limits on your calls, including max per-minute rate, max number of minutes per call, or max total cost per call. You can also specify to use only "premium" call routes, which are often only very slightly higher, but of best call quality, and almost always still less than their competitors.
You must supply your own ATA (Analog Telephone Adapter), VoIP phone, or soft phone and configure it yourself.