Yes, it is possible to start a business using only a phone. In fact, the advancement of technology and mobile connectivity has made it easier than ever to launch and operate a business solely through a smartphone. Here is a detailed answer explaining how it can be done:

1. Idea Generation and Research:
Using a smartphone, you can conduct market research, brainstorm business ideas, and validate your concepts. You can search for industry trends, competitors, and target markets using search engines, social media platforms, and dedicated business research apps.

2. Business Planning and Documentation:
There are numerous mobile apps available that allow you to create business plans, financial projections, and other necessary documents. Apps like LivePlan, StratPad, and Bizplan offer comprehensive business planning features that can be accessed and edited directly from your phone.

3. Communication and Collaboration:
Your smartphone allows you to communicate with potential partners, suppliers, and customers through various channels. Email, messaging apps, and social media platforms enable you to engage in business discussions, negotiate deals, and build relationships. Collaboration tools like Slack, Trello, or Asana can also be accessed on your phone to manage projects and teams remotely.

4. Marketing and Advertising:
With a smartphone, you can create and manage marketing campaigns through social media platforms like Facebook, Instagram, and Twitter. You can design graphics, write content, and schedule posts using mobile apps such as Canva, Buffer, or Hootsuite. Additionally, you can track the performance of your marketing efforts using analytics apps like Google Analytics or Facebook Ads Manager.

5. Sales and Customer Relationship Management (CRM):
Your phone can serve as a point-of-sale device through mobile payment solutions like Square, PayPal, or Stripe. You can manage customer relationships using CRM apps like HubSpot, Zoho CRM, or Salesforce, allowing you to track leads, manage contacts, and monitor sales pipelines.

6. Accounting and Finance:
Various accounting apps like QuickBooks, FreshBooks, or Xero are available on smartphones, enabling you to track income, expenses, and generate invoices. These apps often integrate with banking and payment systems, providing real-time financial data and facilitating financial management on the go.

7. Operations and Project Management:
Your smartphone can be used to manage day-to-day operations and projects. Task management apps like Todoist, Evernote, or Wunderlist help you organize and prioritize tasks, set reminders, and collaborate with team members remotely. Additionally, cloud storage services like Google Drive or Dropbox allow you to access and share files from your phone.

References:
- "The Best Business Plan Software" (The Blueprint): https://www.fool.com/the-blueprint/business-plan-software/
- "The 15 Best Slack Alternatives for Team Communication" (HubSpot): https://blog.hubspot.com/marketing/slack-alternatives
- "The 10 Best Social Media Management Apps" (HubSpot): https://blog.hubspot.com/marketing/best-social-media-management-apps
- "The 5 Best Mobile Payment Apps" (The Balance Small Business): https://www.thebalancesmb.com/best-mobile-payment-apps-4160009
- "The 7 Best CRM Apps for Small Business in 2021" (The Blueprint): https://www.fool.com/the-blueprint/best-crm-apps/