Operating systems have control over which keyboards they open for each input type. I have written some code that changes the types used by inputs on a page. Adding this to your question may resolve your situation:
<script>
$(document).ready(function(){
$('input[type=tel]').prop('type', 'number');
})
</script>
Hopefully type=number will be sufficient for you. If not, type=text is always an option that should open the full keyboards.