Attention Iowa Legislature: Please stop doing that.
The proper style is with dashes, and preferably parentheses for area codes, no matter how many advertisements appear otherwise. Periods aren’t supposed to be used for dates, either, USA Today redesign notwithstanding.
It is not an IP address. It is not a decimal number. It is a series of digits for a specific purpose with a format that was agreed upon decades ago.
(End copy editor/design rant.)