I'm sorry I don't really have an answer to your question but I did want to ask, how much cheaper did you find the phone for?
Because Straight Talk marks the price of their phones up by $30 or $45 but then the phones come with a free 30 day service plan card which is itself a value of $30 or $45(depends on whether its the unlimited plan). Under Straight Talk the E71 only works with the $45 unlimited plan so the phone is marked $45 dollars up from market price and comes with the "free" $45 dollar unlimited card. So basically you can only buy the phone and 30 day card together. And you'd be buying that $45 plan anyway if you were going activate another phone for Straight Talk.
hope this helped!