Weigh all the "pros" and "cons" before decide on such an act. But do not take this matter extremely seriously.
Most often, we are concerned about how we look in the eyes of someone going to call. Most likely, the man will appreciate your courage, because the call clearly demonstrates an interest in it.
Also, we are afraid to call if you do not know what to say at this man. Think about it, because your partner may be experiencing the same feelings! Fear of rejection (or seem ridiculous) inherent to any person, regardless of gender.
If you are afraid that a man thinks you are too available - do not worry for nothing. If you have self-esteem, one call is unlikely to shake your confidence, and the interlocutor feel it even by voice.
Ask yourself, do you like to take the initiative, or you basically wait for it only on men? If you do not mind the possibility to take the first step towards a new relationship, will only come up with an excuse to call.
The preposition can be any, depending on the situation and the personality of a particular man, but definitely should not be calling him with complaints ("Why did not you call?"). This will alienate any man. Use your imagination and sense of humor - and are sure to find a good reason to call.
Do not be too obtrusive. Men appreciate a sense of proportion not less sincerity. His call, you have already shown that they are willing to further develop relations. It was the turn of your men to take the initiative in their hands.
If you prefer to wait for a call from a gentleman, just tell him that the exchange of phone numbers. So you will avoid unnecessary ambiguity.
By and large, it does not matter who makes the decisive call. Throw out the stereotypes and act, guided by your intuition. In the worst case, you'll find that with the person on the other end you are on the way, at best - both will be on the threshold of something new and wonderful!