I have a masked field for the phone number inside the grid:

<eo:MaskedEditColumn DataField="CellPhone" Width="120" HeaderText="Cell Phone" ClientSideEndEdit="validatePhone">
<MaskedEdit runat="server" Width="120" ControlSkinID="None">
<eo:MaskedEditSegment SegmentType="Number" MaxValue="1" MinValue="1" />
<eo:MaskedEditSegment SegmentType="Literal" Text="-" />
<eo:MaskedEditSegment SegmentType="Mask" Mask="000" />
<eo:MaskedEditSegment SegmentType="Literal" Text="-" />
<eo:MaskedEditSegment SegmentType="Mask" Mask="000" />
<eo:MaskedEditSegment SegmentType="Literal" Text="-" />
<eo:MaskedEditSegment SegmentType="Mask" Mask="0000" />
</MaskedEdit>
</eo:MaskedEditColumn>

I need to validate that the user enters the entire number, so I call ClientSideEndEdit="validatePhone"

function validatePhone(cell) {
var cellValue = cell.getValue();
var error = "";
var stripped = cellValue.replace(/[\(\)\.\-\ ]/g, '');

if (cellValue == "") {
error = "You didn't enter a phone number.\n";
} else if (isNaN(parseInt(stripped))) {
error = "The phone number contains illegal characters.\n";
} else if (!(stripped.length == 11)) {
error = "The phone number is the wrong length. Make sure you included an area code.\n";
}
window.alert(error);
return false;

}

However on the function the cell value is undefined and the function failed