I was in Madrid recently for a brief stay and had trouble using the Telefonica telephone booths (for local calls, with Euro coins). I eventually was able to make my calls, but I fumbled around too much and did not find the onboard instructions to be helpful. So, what is the proper procedure??. For example, pick up the handset, insert coin(s) (how much?), punch in the phone number? And how do I know if additional coins are needed? Thanks.