:D:D
My sister did just that, and I thought exactly the same thing, why not spend the money for guaranteed quality?
I find VOIP calls start to get echoey after about 25mins - assume the provider is telling me I've spent my 10c and it's time to hang up and call back.
And recently I've found calling landlines from my mobile - Telstra - get echoes from the getgo. Called, complained, said that it was happening on both iphones, so maybe a Telstra problem. The phone person wanted to reset one of the phones to see what was going on, but wasn't really sure what data would be lost...

