How to strip whitespace from fields filtered in graph API queries

I am using Microsoft graph to do search on the mobilePhone field in active directory, using the startsWith keyword.

$filter=startsWith(mobilePhone,'+44765')

see https://learn.microsoft.com/en-us/graph/query-parameters?tabs=http#odata-system-query-options

However, the data exists with no standardised formatting

For example
+44 765 432 109
or
+44 765 432109
+44 765432 109

So the filter applied will not work across all the data unless spaces are included at the relevant points.
Therefore it is impossible to query all the data at the same time.

If this were SQL one would use something like

WHERE TRIM(mobilePhone) LIKE '<filter>%'

which would allow the filter to be applied without spaces, across all records.

With the graph API is there a way of stripping whitespace out for fields in the query filter, so that the filter data does not need to worry about space formatting, in the same way that is possible with SQL?

OData protocol supports trim function but not the Graph API.

The request with trim

https://graph.microsoft.com/v1.0/users?$filter=startsWith(trim(mobilePhone),'%2B420')&$count=true
Header: ConsistencyLevel:eventual

will return Request_UnsupportedQuery error code

Only way is to combine all forms

https://graph.microsoft.com/v1.0/users?$filter=startsWith(mobilePhone,'%2B44765') or startsWith(mobilePhone,'%2B44 765')&$count=true