Regular expression for validate Mobile number using RegularExpressionValidator in ASP.Net

Hi Mahesh1986,

Refer the below sample.

HTML

<asp:TextBox runat="server" ID="txtMobileNumber" />
<br />
<asp:RequiredFieldValidator ID="rfvMobNo" runat="server" ErrorMessage="Required"
    Display="Dynamic" ValidationGroup="Validate" ForeColor="Red" ControlToValidate="txtMobileNumber"></asp:RequiredFieldValidator>
<asp:RegularExpressionValidator ID="revMobNo" runat="server" ErrorMessage="Invalid Mobile Number."
    ValidationExpression="^([0-9]{10})$" ControlToValidate="txtMobileNumber" ValidationGroup="Validate"
    ForeColor="Red" Display="Dynamic"></asp:RegularExpressionValidator>
<br />
<asp:Button Text="Submit" runat="server" OnClick="Submit" ValidationGroup="Validate" />

Screenshot