phonefactor for terminal services

I don't think you should worry about the reliability of the telephone network for phonefactor. When you think about it, telephone networks are engineered for 5 9's reliability while IP networks tend to have problems. Good thing also is that you could really think of it as more than one telephone network. Users can choose their wireless network or change it to their wireline network if the wireless phone is stolen, lost, out of range, out of battery, etc. I actually think of it as more secure than PC.
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