Transfer contacts between Betamax and Dellmont VoIP calling softwares

Betamax/Dellmont keep on launching new brands with reduced call rates and after increasing the calling rate previously launched brands. For eg., they were offering half cent call with smartvoip, then increased to 1.1 cent and lunched actionvoip, jumblo and rynga with 0.7 cents and again increased the rates. Switching VoIP company is never an easy solution, and when it comes to address book