You can get an Estonian phone number through Twilio, MessageBird, Skype, or Travelsim (who offer Estonian SIM cards at a reasonable price).
You can purchase .ee domain(s) through Zone.
Your company's postal address is Sepapaja 6, Tallinn 15551, Estonia. All physical mail you receive will be digitized and forwarded to you via email.
All business-related communication costs are considered business expenses and can be covered using your company's money.
How can I get an Estonian phone number or domain?