def METHOD_NAME(num_subs: int, input_file: str):
    active_sids = _load_subs(num_subs)
    update_subs_reqs = []
    for sid in active_sids:
        config = Non3GPPUserProfile(
            apn_config=[APNConfiguration(service_selection=TEST_APN_UPDATE)],
        )
        data = SubscriberData(sid=sid, non_3gpp=config)
        update = SubscriberUpdate(data=data)
        update_sub_req_dict = json_format.MessageToDict(update)
        update_subs_reqs.append(update_sub_req_dict)
    with open(input_file, 'w') as file:
        json.dump(update_subs_reqs, file, separators=(',', ':'))