which frequencies are all?

Recently, Arden Prinz posted:

I was approaching class C airspace for landing at the primary airport
for which the class C airspace is designated and I listened to the
ATIS. The ATIS said "all frequencies are combined on
TowerFrequency". So I tuned to TowerFrequency and made my radio
call to approach. The response that I got was that I needed to call
approach on the approach frequency. So, I guess that begs the
question ... when the ATIS says "all frequencies are combined", which
frequencies are included in "all frequencies"?

I would have presumed it meant exactly as you did. Out of curiosity, what
happened next? Did they give you the approach frequency, change the ATIS,
or did you get the same controller when you changed frequencies?

Neil