Globelines under area Code "38"

Landline calls originating from Bohol or Tagbilaran bear the area code 36. How can you tell then if it is from a PLDT or Globelines subscriber? Here are the list of Globeline prefixes under this area code:

500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547