It's our old friend Mr. Clip-Art Mug Hoister. Fairly generic match; don't know why they'd want to put the phone number on the front and nothing else. If you needed to call the place on a regular basis, you'd probably know the number.

Perhaps the number's on the front because John and Carl wanted their names on the back.

Henry Wilhelm was also an owner, and thanks to this site on the accomplishments of Volga Germans, we have some pictures of the place.