Как получить select id в POST ?

if( isset( $_POST['smsinv'] ) )
{
    $land = 375;
    $phoneget = $_POST['phone'];
    $phone = $land . $phoneget;
echo $message;	
}

<form class="form-horizontal" method="post">
	<span id="reg1">
		<div class="form-group">
			<label for="mail" class="col-sm-4 control-label">Укажите страну:</label>
			<div class="col-sm-6">
				<select id="land">
					<option value="375">Беларусь +375</option>
					<option value="7">Россия +7</option>
				</select>
			</div>
		</div>
		<div class="form-group">
			<label for="mail" class="col-sm-4 control-label">Номер телефона:</label>
			<div class="col-sm-6">
				<input placeholder="Например, 299490049" type="text" class="form-control" id="phone" name="phone">
			</div>
		</div>
			<div class="form-group">
			<div>
	          	<input type="submit" style="color: #fff; background: #f56142;    border-radius: 25px;margin-top:20px;    border: none;    width: 100%;    text-align: center;" name="smsinv" value="Отправить">
		    </div>
		</div>
	</span>
		</form>