Это сложный пример, но он обрабатывает не только телефонные номера. Это закомментировано до смерти.

#widgets.py

import tkinter as tk, re
from dataclasses import dataclass, field
from typing import List, Pattern, Iterable
from copy import deepcopy

Char: Pattern = re.compile('[a-z0-9]', re.I)


''' FormEntryFormat_dc
    this serves as a configuration for the behavior of FormEntry
'''
@dataclass
class FormEntryFormat_dc:
    valid      :Pattern        = None                        #pattern to validate text by
    separator  :str            = None                        #the separator to use
    marks      :List           = field(default_factory=list) #list of positions to apply separator
    strict     :bool           = False                       #True|False strict typing
        
    def config(self, ascopy:bool=True, **data):
        c = deepcopy(self) if ascopy else self
        for key in c.__dict__:
            if key in data:
                c.__dict__[key] = data[key]                  #assign new value
        return c
    
    
#prepare a few formats        
TimeFormat   = FormEntryFormat_dc(re.compile('^(\d{1,2}(:(\d{1,2}(:(\d{1,2})?)?)?)?)?$'      ), ':' , [2, 5])
DateFormat   = FormEntryFormat_dc(re.compile('^(\d{1,2}(\\\\(\d{1,2}(\\\\(\d{1,4})?)?)?)?)?$'), '\\', [2, 5])
PhoneFormat  = FormEntryFormat_dc(re.compile('^(\d{1,3}(-(\d{1,3}(-(\d{1,4})?)?)?)?)?$'      ), '-' , [3, 7], True)   
PhoneFormat2 = FormEntryFormat_dc(re.compile('^(\d{1,3}(-(\d{1,7})?)?)?$'                    ), '-' , [3]   , True)   


''' FormEntry
    an entry with format behavior
'''
class FormEntry(tk.Entry):
    @property
    def input(self) -> str:
        return self.get()
        
    def offset(self, separator:str, marks:Iterable):
        sep_marks = [] #cache for positions of already inserted separators
        offset    = 0  #the overall offset between inserted and expected separator marks
        
        #get a mark for every current separator
        for i, c in enumerate(self.input):
            if c == separator:
                sep_marks.append(i)
        
        #if any sep_marks ~ subtract the value of sep_marks last index 
        #~from the value of the corresponding index in marks
        n = len(sep_marks)
        if n:       
            offset = max(0, marks[n-1]-sep_marks[-1])
            
        return offset
    
    def __init__(self, master, frmt:FormEntryFormat_dc, **kwargs):
        tk.Entry.__init__(self, master, **kwargs)
        
        self.valid = frmt.valid
        if self.valid:
            #register validatecommand and assign to options
            vcmd = self.register(self.validate)
            self.configure(validate="all", validatecommand=(vcmd, '%P'))
            
        if frmt.marks and frmt.separator:
            #bind every key to formatting
            self.bind('<Key>', lambda e: self.format(e, frmt.separator, frmt.marks, frmt.strict))
        
    def validate(self, text:str):      
        return not (self.valid.match(text) is None) #validate with regex

    def format(self, event, separator:str, marks:Iterable, strict:bool):
        if event.keysym != 'BackSpace':             #allow backspace to function normally
            i = self.index('insert')                #get current index
            if Char.match(event.char) is None and (i in marks or not strict):
                event.char = separator              #overwrite with proper separator
            else:
                #automatically add separator
                if i+self.offset(separator, marks) in marks:
                    event.char = f'{separator}{event.char}'
                    
            self.insert(i, event.char)              #validation will check if this is allowed
            
            return 'break'

#main.py (OOP style)

import widgets as ctk #custom tk
import tkinter as tk

class Main(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        
        self.title("Formatted Entry")

        self.grid_columnconfigure(2, weight=1)

        #create labels
        self.labels = ['time', 'date', 'phone', 'phone2']
        for n, label in enumerate(self.labels):
            tk.Label(self, text=f'{label}: ', width=14, font='consolas 12 bold', anchor='w').grid(row=n, column=0, sticky='w')

        #create entries
        self.entries = []
        for n, format in enumerate([ctk.TimeFormat, ctk.DateFormat, ctk.PhoneFormat, ctk.PhoneFormat2]):
            self.entries.append(ctk.FormEntry(self, format, width=14, font='consolas 12 bold'))
            self.entries[-1].grid(row=n, column=1, sticky='w')
        
        #form submit button        
        tk.Button(self, text='submit', command=self.submit).grid(column=1, sticky='e')
            
    def submit(self):
        for l, e in zip(self.labels, self.entries):
            print(f'{l}: {e.input}')
        


Main().mainloop() if __name__ == "__main__" else None

#main.py (procedural style)

import widgets as ctk #custom tk
import tkinter as tk

if __name__ == "__main__":
    root = tk.Tk()
    root.title("Formatted Entry")
    root.grid_columnconfigure(2, weight=1)

    #create labels
    labels = ['time', 'date', 'phone', 'phone2']
    for n, label in enumerate(labels):
        tk.Label(root, text=f'{label}: ', width=14, font='consolas 12 bold', anchor='w').grid(row=n, column=0, sticky='w')

    #create entries
    entries = []
    for n, format in enumerate([ctk.TimeFormat, ctk.DateFormat, ctk.PhoneFormat, ctk.PhoneFormat2]):
        entries.append(ctk.FormEntry(root, format, width=14, font='consolas 12 bold'))
        entries[-1].grid(row=n, column=1, sticky='w')
     
    def submit():
        for l, e in zip(labels, entries):
            print(f'{l}: {e.input}')
            
    #form submit button        
    tk.Button(root, text='submit', command=submit).grid(column=1, sticky='e')
    
    root.mainloop()

Я использовал комбинацию обоих этого примера трассировки переменных tkinter и объединил его с этим ответом, я не уверен на 100%, что это правильное американское форматирование, потому что я живу в Великобритании и здесь мы форматируем вещи по-разному, но это грубый пример того, как это будет работать:

# Python program to trace
# variable in tkinter


from tkinter import *
import re

root = Tk()

my_var = StringVar()

# defining the callback function (observer)


def phone_format(phone_number):
    try:
        clean_phone_number = re.sub('[^0-9]+', '', phone_number)
        formatted_phone_number = re.sub(
            r"(\d)(?=(\d{3})+(?!\d))", r"\1-", "%d" % int(clean_phone_number[:-1])) + clean_phone_number[-1]
        return formatted_phone_number
    except ValueError:
        return phone_number


def my_callback(var, indx, mode):
    my_var.set(phone_format(my_var.get()))
    label.configure(text=my_var.get())


my_var.trace_add('write', my_callback)

label = Label(root)
label.pack(padx=5, pady=5)

Entry(root, textvariable=my_var).pack(padx=5, pady=5)

root.mainloop()

Альтернатива

# Python program to trace
# variable in tkinter


from tkinter import *
import phonenumbers
import re

root = Tk()

my_var = StringVar()

# defining the callback function (observer)


# def phone_format(phone_number):
#     try:
#         clean_phone_number = re.sub('[^0-9]+', '', phone_number)
#         formatted_phone_number = re.sub(
#             r"(\d)(?=(\d{3})+(?!\d))", r"\1-", "%d" % int(clean_phone_number[:-1])) + clean_phone_number[-1]
#         return formatted_phone_number
#     except ValueError:
#         return phone_number

def phone_format(n):                                                                                                                                  
    # return format(int(n[:-1]), ",").replace(",", "-") + n[-1]   
    # return phonenumbers.format_number(n, phonenumbers.PhoneNumberFormat.NATIONAL)
    formatter = phonenumbers.AsYouTypeFormatter("US")
    for digit in re.findall(r'\d', n)[:-1]:
        formatter.input_digit(digit)
    return formatter.input_digit(re.findall(r'\d', n)[-1])



def my_callback(var, indx, mode):
    print(my_var.get())
    my_var.set(phone_format(my_var.get()))
    label.configure(text=my_var.get())

def callback(event):
    entry.icursor(END)


my_var.trace_add('write', my_callback)

label = Label(root)
label.pack(padx=5, pady=5)

entry = Entry(root, textvariable=my_var)
entry.bind("<Key>", callback)
entry.pack(padx=5, pady=5)


root.mainloop()

Это было мое решение с использованием phonenumbers из PyPi, которое, казалось, заставило его работать.

Вот процедурный пример. Пример очень сильно прокомментирован.

import tkinter as tk, re
from dataclasses import dataclass, field
from typing import List, Pattern, Iterable
from copy import deepcopy

Char: Pattern = re.compile('[a-z0-9]', re.I)


''' FormField_dc
    this serves as a configuration for the behavior of form_field
'''
@dataclass
class FormEntryFormat_dc:
    valid      :Pattern        = None                        #pattern to validate text by
    separator  :str            = None                        #the separator to use
    marks      :List           = field(default_factory=list) #list of positions to apply separator
    strict     :bool           = False                       #True|False strict typing
        
    def config(self, ascopy:bool=True, **data):
        c = deepcopy(self) if ascopy else self
        for key in c.__dict__:
            if key in data:
                c.__dict__[key] = data[key]                  #assign new value
        return c
    
    
#prepare a few formats        
TimeFormat   = FormEntryFormat_dc(re.compile('^(\d{1,2}(:(\d{1,2}(:(\d{1,2})?)?)?)?)?$'      ), ':' , [2, 5])
DateFormat   = FormEntryFormat_dc(re.compile('^(\d{1,2}(\\\\(\d{1,2}(\\\\(\d{1,4})?)?)?)?)?$'), '\\', [2, 5])
PhoneFormat  = FormEntryFormat_dc(re.compile('^(\d{1,3}(-(\d{1,3}(-(\d{1,4})?)?)?)?)?$'      ), '-' , [3, 7], True)   
PhoneFormat2 = FormEntryFormat_dc(re.compile('^(\d{1,3}(-(\d{1,7})?)?)?$'                    ), '-' , [3]   , True)   


''' FormField
    An entry field intended to force a specific format while the user types
'''
def form_field(master, f:FormEntryFormat_dc, **kwargs) -> tk.Entry:
    entry = tk.Entry(master, **kwargs)
    
    def offset(separator:str, marks:Iterable):
        sep_marks = [] #cache for positions of already inserted separators
        offset    = 0  #the overall offset between inserted and expected separator marks
        
        #get a mark for every current separator
        for i, c in enumerate(entry.get()):
            if c == separator:
                sep_marks.append(i)
        
        #if any sep_marks ~ subtract the value of sep_marks last index 
        #~from the value of the corresponding index in marks
        n = len(sep_marks)
        if n:       
            offset = max(0, marks[n-1]-sep_marks[-1])
            
        return offset
        
    #test text against validity conditions
    def validate(text):
        #if numeric check is True and len(text) > 0 
        return not (f.valid.match(text) is None) #validate with regex
        
    if f.valid:
        #register validatecommand and assign to options
        vcmd = entry.register(validate)
        entry.configure(validate="all", validatecommand=(vcmd, '%P'))
            
    #add separators when entry "insert" index equals a mark  
    #~and separator isn't already present
    def format(event, separator:str, marks:Iterable, strict:bool):
        #allow backspace to function normally
        if event.keysym != 'BackSpace':
            i = entry.index('insert')                #get current index
            if Char.match(event.char) is None and (i in marks or not strict):
                event.char = separator              #overwrite with proper separator
            else:
                #automatically add separator
                if i+offset(separator, marks) in marks:
                    event.char = f'{separator}{event.char}'
                    
            entry.insert(i, event.char)              #validation will check if this is allowed
            
            return 'break'
                
    
    if f.marks and f.separator:           
        #bind every keypress to formatting
        entry.bind('<Key>', lambda e: format(e, f.separator, f.marks, f.strict))
    
    
    return entry
    

##USAGE EXAMPLE
if __name__ == "__main__":
    root = tk.Tk()
    root.title("Formatted Entry")
    root.grid_columnconfigure(2, weight=1)

    #create labels
    labels = ['time', 'date', 'phone', 'phone2']
    for n, label in enumerate(labels):
        tk.Label(root, text=f'{label}: ', width=14, font='consolas 12 bold', anchor='w').grid(row=n, column=0, sticky='w')

    #create entries
    entries = []
    for n, format in enumerate([TimeFormat, DateFormat, PhoneFormat, PhoneFormat2]):
        entries.append(form_field(root, format, width=14, font='consolas 12 bold'))
        entries[-1].grid(row=n, column=1, sticky='w')
     
    def submit():
        for l, e in zip(labels, entries):
            print(f'{l}: {e.get()}')
            
    #form submit button        
    tk.Button(root, text='submit', command=submit).grid(column=1, sticky='e')
    
    root.mainloop()