I need all my leads to show what time zone they are in. I created a formula that takes their phone numbers area code and automatically shows their time zone. My issue is that I recently synced leads from pardot and the phone number format is different. The synced leads are showing as 1.235.524.5641 whereas the previous leads I have are in the format 2545856589. Is there a way that I can get these new leads to change the format of their phone numbers? Or possibly update my code to allow this new format to match to their corresponding time zones?
Thanks!

Here is the current formula I have. 

Data Type Formula    
if( ISBLANK(Phone),"--", 

if(CONTAINS("206:209:213:253:310:323:360:408:415:425:503:509:510:530:559:562:604:619:626:650:661:702:707:714:760:775:778:805:818:831:858:867:909:916:925:949:951:971:236:250:604:778:867", left(SUBSTITUTE( Phone , "(", ""),3)),"UTC-8 Pacific", 

if( CONTAINS("208:250:303:307:385403:406:435:480:505:520:602:623:719:720:780:801:928:970:403:587:780", left(SUBSTITUTE( Phone , "(", ""),3)),"UTC-7 Mountain", 

if( 
CONTAINS("204:205:210:214:217:218:224:225:228:251:254:256:262:270:281:306:308:309:312:314:316:318:319:320:325:334:337:361:402:405:409:414:417:430:432:469:479:501:504:507:512:515:563:573:580:601:605:608:612:615:618:620:630:636:641:651:660:662:682:708:712:713:715:731:763:769:773:785:806:815:816:817:830:832:847:901:903:913:915:918:920:931:936:940:952:956:972:979:985:204:306:431:639:807", left(SUBSTITUTE( Phone , "(", ""),3)),"UTC-6 Central", 

if(CONTAINS("201:202:203:207:212:215:216:219:226:229:231:234:239:240:248:252:267:269:276:289:301:302:304:305:313:315:321:330:336:339:345:347:351:352:386:404:407:410:412:416:418:419:434:438:440:443:450:470:475:478:484:502:508:513:514:516:517:518:519:540:551:561:567:570:571:585:586:603:606:607:609:610:613:614:616:617:631:646:647:649:678:703:704:705:706:716:717:718:724:727:732:734:740:754:757:770:772:774:781:786:802:803:804:810:813:814:819:828:835:843:845:848:856:857:859:860:862:863:864:865:876:878:904:905:908:910:912:914:917:919:937:941:947:954:959:973:978:980:226:249:289:343:365:416:437:438:450:514:519:579:581:613:647:705:819:873:905", left(SUBSTITUTE( Phone , "(", ""),3)),"UTC-5 Eastern", 

if( CONTAINS("506:709:902",LEFT(SUBSTITUTE(Phone,"(",""),3)),"UTC-4 Atlantic", 

if( CONTAINS("800:877",LEFT(SUBSTITUTE(Phone,"(",""),3)),"Toll Free","Other" 
)))))))