Phone Number type definition for GraphQL back-end.

phone.number.type.js

import {
    GraphQLObjectType,
    GraphQLInputObjectType,
    GraphQLString,
    GraphQLNonNull
} from 'graphql';

var ObjectType = new GraphQLObjectType({
    name: 'PhoneNumber',
    fields: () => ({
        number: { type: new GraphQLNonNull(GraphQLString) },
        description: { type: GraphQLString }
    })
});

var InputType = new GraphQLInputObjectType({
    name: 'PhoneNumberInput',
    fields: () => ({
        number: { type: new GraphQLNonNull(GraphQLString) },
        description: { type: GraphQLString }
    })
});

export {
    ObjectType,
    InputType
};

Just a suggestion, try to look for up-to-date content. The post where I used that gist was typed long time ago and related tasks are not done this way right now.

I've been checking and Apollo Server repository was create on April 17, 2016 and this gist code was created on August 27, 2017.

In that date Apollo Server was irrelevant yet.