Hello 'billbish',
You say the buyer 'tried' to call you. Were you out? Call Display? Did you recently get a notice from ebay telling you that this buyer had requested your contact information? Have you checked your regular email?
There may have been something the buyer needed to say most urgently and was afraid you would have shipped the item before reading your messages. Just a guess. Or has she already received it? Perhaps she has a question she wishes to discuss earnestly and at length, away from the 'word limit' of ebay messages. Either way, when a buyer pays, she gets your name and address on her paypal receipt, - just like you get hers, - so a phone number is no big deal.
It is not usual for a buyer to call, but it is most likely some silly innocent thing about the order. As 'hereiam' says, - pick up the receiver and find out what she wants. If you are simply not comfortable doing that, then now's the time to send her a message explaining that you are away from the phone most of the time but is there anything you can do to assist her, that sort of thing. Assure her you check your messages frequently and wil get back to her soon as possible.