unknown field in struct literal

I'm trying to create a struct, and it is giving me an error, telling me the field is unknown.

The struct I am trying to initialize is:

package yelk

type PhoneOptions struct {
    phone string
    cc    string
    lang  string
}

And I'm trying to initialize a PhoneOptions struct in cli.go like this:

number := os.Args[1]
phoneOptions := yelk.PhoneOptions{phone: number}

I do go run cli.go 5555555555 but it gives me an error

./cli.go:29: unknown yelk.PhoneOptions field 'phone' in struct literal

All The StackOverflow posts I've seen with this error seem to be from nested structs. I'm wondering what I'm doing wrong. cli.go will give this error if I just try to run go build on it, so I don't think it's the inputs I've been running it with.

Any idea why this happens?

Fields that start with lower case characters are package internal and not exposed, If you want to reference the field from another package it needs to start with an upper case character, eg.

package yelk

type PhoneOptions struct {
    Phone string
    Cc    string
    Lang  string
}

and then

number := os.Args[1]
phoneOptions := yelk.PhoneOptions{Phone: number}