Perhaps one of the elatior hybrids. Zone 7 isn't really relevant since this is strictly a summer bedding plant outside very warm climates.

floral, the large-leafed varieties are often used as house plants here in the US. I don't think this is what we call a bedding Begonia; the leaves appear to be different than the ones we use for annual beds.

I am pretty sure this is one of the tuberous hybrids, like floral said. Larger leafed begonias typically grown as houseplants rarely have flowers as complex, full or as striking as those depicted. They tend to be small and quite simple.

btw, there are a variety of different begonias, including wax begonias, that are grown as annual bedding plants

The tender Begonias like this one or wax begonias do not make good houseplants and are seldom used as such other than as temporary decor, often given as gifts. The Begonias which survive indoors year after year, such as B. rex, are grown for their foliage, not their flowers. This is not one of those.