Single value in phone_id
If you store phone numbers in phone_id and you need to populate the phone attribute using a value from phone_id, you can set up a scenario use case with a Repeat trigger or a Now/On date trigger.
However, the above will only work when phone_id contains only 1 value, a string.
Multiple values in phone_id
If, on the other hand, your phone_id contains multiple values, which is a list of strings, you can use the code below and insert it in the Set attribute node.
{% if customer_ids.phone_id is string %}
{{customer_ids.phone_id}}
{% elif customer_ids.phone_id is iterable and customer_ids.phone_id | length > 1 %}
{{customer_ids.phone_id |last}}
{% endif %}The code above checks if phone_id is a string; if yes, it will insert the single value that is there. However, if it's a list of strings, it will populate phone with the last value from the list stored in the phone_id
Note
Always make sure to TEST the implementation above on the testing customer profile to verify if all works as expected before applying it LIVE.