How To Allow Only Numbers in Phone Number Field in Visual Force Page

If your trying to restrict your phone number field to accept only Numbers in visual force page you can use the below simple JavaScript code to achieve this easily.

<script>

function isNumber(evt) {
        evt = (evt) ? evt : window.event;
        var charCode = (evt.which) ? evt.which : evt.keyCode;
        if (charCode > 31 && (charCode < 48 || charCode > 57)) {
            return false;
        }
}

</script>

<apex:inputfield value="{!c.Phone__c}" id="boPhone" onkeypress="return isNumber(event)"/>