what the circle looks like GOTHAM BOLD, with a little more weight... but I'm not so sure, the "U" does not fit.
the inside I think this hand painted.

maybe someone knows the exact font.

Thanks.
This is a very old sign, maybe 1940's.
The kind of typeface I imagine Tobias Frere-Jones used as a reference for Gotham.

That version of the Bell System logo was first introduced in 1939, and persisted until Saul Bass created his iconic revision in 1969.

“Public Telephone” resembles Akzidenz-Grotesk (the |C| especially), but your sample has a much rounder |O| than the one in A-G. Without knowing an approximate date for the sign, it’s hard to pin down the original face.

These digital typefaces could help you approximate the look:
http://www.myfonts.com/fonts/marksimonson/proxima-nova/
http://www.google.com/fonts/specimen/Raleway
http://www.typography.com/fonts/gotham/overview/

Plax and all,

Do you know the Frere-Jones font Nobel that Tobias designed for Font Bureau?
http://www.fontbureau.com/fonts/Nobel/styles/

Dutch Type Library has a different digital version of Nobel.
http://www.dutchtypelibrary.nl
(See Nobel Bold)

Thanks KT.
Interesting website showing the development of the porcelain signs.
Unfortunately no info about type design.

http://www.telephonesigns.com/bellsigns.htm

Nobel would work as well, but the counters on the B aren’t as long/horizontal as the ones on your sample.

Font Bureau used to sell a typeface called Bonn Caps (designed by Neville Brody) that, save for a pointy |N|, is a very good match to your sample. Unfortunately, I can’t find a legitimate source for it.

Thanks for the information mkstudio & kthomps5... Interesting.

So interesting to read about the history of Bell in light of the "net neutrality" issues in the news right now.

Thanks so much for your info KT.

*A hilarious site addressing privacy and information in the telephone era:-)
http://www.grayflannelsuit.net/blog/saul-bass-att-logo-design-1969

*Good article:
http://omahaworks.net/bell-system---we-history.html

The Creator of the Bell and AT&T Logos
"The [Bass & Yager] design firm had created the famous bell symbol for the nationwide phone monopoly in the late 1960s. This icon--which achieved a remarkable 93 percent recognition rate in the United States [emphasis added] --aspired to the simplicity and directness of a sans serif letterform. In 1984, the familiar bell symbol was transferred to the divested "Baby Bells," and Bass & Yager designed a striated sphere for AT&T, aiming to signify the corporation's international stature and the ascendance of digital communications."

The AT&T Long Lines Department was responsible for connecting the local Bell companies together to provide long distance telephone communication between each Bell company. Here are two logos representing the time period between 1939 and 1963 and the time period after 1969.