Function build_call_push_subscription_request 

pub fn build_call_push_subscription_request(
    owner_nsec: String,
    device_pubkey_hex: String,
    subscription_id: Option<String>,
    platform_key: String,
    push_token: String,
    apns_topic: Option<String>,
    is_release: bool,
    server_url_override: Option<String>,
) -> Option<MobilePushSubscriptionRequest>

Register a device for incoming call wakeups on the existing notification service.