When having a list that contains E164 formatted values for phone numbers, the filter only accepts values that are without blanks.

1. Create a column on the [incident] table called as phone_number which is of type Phone Number (E164)
2. Now go to the [incident] form and configure this field in the list and form layout.
3. Enter the Values phone_number for 3 or 4 incidents.
   Example : Choose country as Netherlands and Enter +31623947387 , +31623947388 , +31623947389 as some phone numbers on different incidents.
4. Because of the field type, the format will be corrected by the system and you will see them as follows:
   +31 6 23947386 , +31 6 23947388 , +31 6 23947387
5. Now in the list view, search for these numbers > nothing is returned.
   URL samples:
6. Use the following URL:
   https://yourinstance.service-now.com/incident_list.do?sysparm_query=phone_numberLIKE%2B31%206%2023947386
7. Nothing is returned.
8. Remove the %20 (replacement for a space in the URL):
   https://yourinstance.service-now.com/incident_list.do?sysparm_query=phone_numberLIKE%2B312062023947386
9. The phone nunber is found.

This is expected behavior and by design in all currently supported releases.