def getlinetype_input():
    """
    Method collects user inputs for line type - TEL or SIP 
    INPUTS: none 
    OUTPUT: Returns str
    """
    valid_values = 'TEL', 'SIP'
    loop = True
    while loop:
        linetype = input(f"Enter line type, {valid_values} (default='TEL'): ")
        if linetype == '':
            return 'TEL'
        if linetype.upper() in valid_values:
            loop = False
        else:
            print(f"Invalid input '{linetype}' >> Expecting [{valid_values}].")
    return linetype.upper()
