Vodafone Qatar, an affiliate of Vodafone Group, said on Monday that access to its network was being affected by technical issues.
The company is working to resolve the issue, Vodafone Qatar said on its official Twitter account.
Several Vodafone customers told Reuters that they were unable to make or receive phone calls.
A spokesman for Vodafone Qatar did not immediately respond to a request for comment.
State-controlled Ooredoo also serves Qatar's mobile communications market.
Saudi Arabia, the United Arab Emirates, Egypt and Bahrain cut diplomatic and transport ties with Qatar on June 5, accusing it of supporting terrorism, a claim which Qatar denies.