Let's arrange for a 7 o'clock wake-up call tomorrow.

Literal

Tomorrow [topic-は], 7-o'clock [at-に] morning-call [object-を] make-receive [arranged-ことにしよう].

モーニングコールをかけてもらう — 'have someone make a morning call (for us)' — uses ~てもらう for receiving a service. ことにしよう ('let's decide to') uses こと + にする (to decide) + volitional ~よう. A hotel-context sentence.