Making a random choice over the phone?

Question

Two people on the phone want to settle a decision by chance. Each should have an equal probability of winning. Flipping a coin won't work because they both can not see the coin and they don't trust each other. (Same problem with drawing cards, rolling dice, and so on.) They don't want to involve a third person or base it on the outcome of a lottery number because they need an immediate decision.

Is there any fair way that a random choice can be made over the phone?

Or is this only possible if both people are in the same room?

Answer 1

Well I would figure they could use instant messaging and figure something out. Now that I think about it there isnt really a viable option if the trust isnt there and no third party can be involved.