Could I have a call at 7.30, please?
- you say this if you're staying in a hotel and you want the receptionist to give you a wake up call at 7.30. (In this sentence, "call" is short for "wake up call" - very specific to a hotel.)
I'd like to make a call to New Zealand, please.
- this means you want to phone somebody in New Zealand yourself, and you're asking for help from the phone operator, or permission from the person who pays for the phone.
You wouldn't say, "Can I have a call to New Zealand?"