I imagine that you are sowing perennial violas and not viola x wittrockiana (pansies). If this is the case, it really depends on the species whether it needs cold treatment or not. Putting dry seed in the freezer does nothing to improve their germination and I cannot understand why the seed companies give this information (also seen on Delphinium packages).

If they are perennials, sometimes the seed needs a moist cold treatment for about 2 to 3 months. This means that you need to sow the seed in soil less mix (ie Promix), water it in, seal it either in a ziplock or a tray with a cover and put the seed in the refrigerator or outdoors (if it is still cold). If the seed is an annual, it doesn't need treatment at all. Just sow it, put in under lights indoors and if the seed is not old, it will germinate in about 1 week to 2 weeks.