HD Voice is probably turned off on your phone. If it is turned on, you will want to reset network settings, and make certain that your software is up to date. I have experienced the same issue, and when I reset my network settings, it eliminated the issue. I had to do this multiple times to make the issue elimination permanent, but I have not experienced this issue since.
Samirav20, We certainly understand wanting to be able to talk and browse the internet at the same. What make and model phone do you have? By chance, have you tried any of the suggestions wadeowen307 suggested?
Thanks for confirming, Samirav20. I'd like to take a look at your account and troubleshoot toward a solution. Please check your private messages for details.