Does anyone know of a texing app that will give me a japanese phone number?

if friends have smart phone, can use line, seems favorite texting app of japanese people (and apparently several other asian countries). had older lady tell me today uses line talk friends , daughter.
won't give japanese cell phone number, i'm pretty sure works phone calls between other line users well.
use viber. seems line. think viber more common among americans , line among japanese people. haven't used both, can't tell works better.
if friends in japan don't have smart phones, fear not. wouldn't have helped have japanese number anyway. cell phone system set strangely here (or perhaps seems strange because of american perspective.) anyway, sms messages available between people using same carriers. however, phones have email address attached them. service free cell phone holder (or pay minimal monthly fee have unlimited access.) these messages can sent american cell phones without trouble. american cellphones have email addresses, aren't advertised in america. it's no issue mail japanese cell american one.
(if aren't america, assume can correct email address cell phone carrier in whatever country you're without trouble. i've been able find these addresses every phone carrier i've ever looked for, including in egypt, don't remember them american ones. included link list of these addresses, don't know how complete countries other america , japan.)
also, these messages don't cost more typical text message. emailed american friend's phone first summer in japan. can't receive picture messages, messages @ no cost. phone's email address depend on phone number , carrier. numbers 9 digit phone number. examples are:
##########@vtext.com verizon
##########@txt.att.net att
##########@messaging.sprintpcs.com
friends have had respond messages in order text me in japan, when texted japan america, had no trouble typing japanese friends' cell email addresses instead of phone number.

bottom line: line or viber easiest option, work if other person has smartphone.
if other person doesn't, it's easiest them email phone , can respond.

hope helps! please don't hesitate contact me if unclear or have more questions! :)

i want app give me local japanese phone number can call or text friends in japan. it's okay if app cost money, , okay if in japanese.

thanks!

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