Make a shorter list by entering letters via DTMF

How to make a list
in a voice app
shorter
by entering letters via
DTMF

Pavel Růžička, January 2012
T-Mobile Czech Republic

Agenda

•List – hidden treasure of VoiceObjects
•When a list is too long
•How to enter letters via DTMF
•Let the user navigate by a letter
•Optimization
•Summary
•Example to import into your project
•Resources

2

List object – a treasure of VoiceObjects
•allows users go through collection of data
•without significant effort of a developer
•it's like an audible excel sheet with unified navigation

3

When a list is too long
Afghanistan
Albania
Algeria
American Samoa • Imagine a list of countries
Andorra
Angola
Anguilla
Antarctica
Antigua And Barbuda
• Isn't it cruel to let the user go
Argentina
Armenia
through 216 items to reach
Aruba
Australia
Turkey?
Austria
Azerbaijan
Bahamas
Bahrain
Bangladesh
Barbados
Belarus
Belgium
Belize
Benin
Bermuda
Bhutan
Bolivia
Bosnia And Herzegowina
...
...
Trinidad And Tobago
Tunisia
Turkey
...
...
Zimbabwe

4

Make the user closer to the target

Taiwan
Tajikistan
Tanzania
• make the list alphabetically
Thailand
Togo
ordered
Tokelau
Tonga
Trinidad And Tobago
Tunisia • offer items starting with a chosen
letter
Turkey
Turkmenistan
Turks And Caicos Islands
Tuvalu • approximatelly 12 items starting with
the same letter
• Turkey is 10th

• isn't that nice? 

5

Is it possible to enter letters via DTMF?

• of course by CCITT it recognizes also A,B,C and D
• but not on common phones. It's too little, it's useless.

• there is other possibility – users know it from
sending SMS
• e.g. for B you need to press the key twice
A-2
B - 22
...
O - 666
...
Z - 9999

6

What do we need to get a letter from DTMF digits?

• input object with grammar for 1-4 digits

• good explanation what you expect from the user

• translation collection

• VALUESUBSTITUTION expression

7

Input with TTG grammar and with translation expression

8

Translation the input result value

9

Digits are translated
– but what if user needs to enter a real digit?

• the approach of translation prevents users to enter the real
value of a key

• we should offer an alternative how to enter any digit

• only one key at once is valid for generating a letter
• we can recognize different key as a request for suppressing the
translation
• if the entered value is not in the translation collection – return the first
pressed key
• 22 will be translated as B
• 963, 7*, 54 are not in translation collection
only first digit will be taken: 9, 7, 5

10

Check if the entered value can be translated
• FINDROW expression to check if the value exists in the
translation collection

11

Translation or assign unchanged value?
• CONDASSIGN expression to conditionally assign translated or
unchanged value
• LEFT to return only the first pressed digit (unchanged value)

12

Wrap it to sequence with confirmation

• Confirmation object to confirm and, if necessary, to correct
information from the preceding dialog

13

Long list - let the user navigate by the first letter

• filter out unnecessary items
Taiwan • copy the collection to a temporary collection
Tajikistan
Tanzania
and then with ITERATE and DELETEROW
Thailand expressions delete redundant items
Togo
Tokelau
Tonga
Trinidad And Tobago
Tunisia
• scroll the list down to the first item
Turkey
Turkmenistan
starting with chosen letter
Turks And Caicos Islands
Tuvalu
• you need to find row index of the item
going through the collection using LOOP
object or ITERATE expression with INDEX
• then update row index of the list
• you have to ensure there is at least one
item starting with the letter

14

Other optimization
• include special chars to the translation collection like _ . @ #
<row>
<col name="key">1</col>
<col name="default">.</col>
</row>
<row>
<col name="default">_</col>
</row>
<row>
<col name="key">*</col>
<col name="default">@</col>
</row>

• since grammar allows to enter 4 digits it's good to translate 4th press of a
key with only 3 letters as well as 3rd letter to help users avoid of
mistyping
<row>
<col name="default">T</col>
</row>
<row>
<col name="default">U</col>
</row>
<row>
<col name="default">V</col>
</row>
<row>
<col name="default">V</col>
</row> 15

More than one letter at once
• enhanced algorithm could allow to enter more than one letter at once
• grammar needs to be changed
• way of confirmation needs to be changed to confirm after whole input
• whole input needs to be splitted by clusters of the same key to collection, then
translated
• real digit in the input could be followed by an asterisk (*) or by 1 wich has no meaning

• could be useful for experienced users, special applications, admin
interfaces
• you can enter alphanumeric password, e-mail address etc...

16

Summary

• create a special input for entering a letter by numbers with proper
grammar
• sequence with confirmation will make it much more useful

• fill the translation collection and implement translation into
postprocessing of the input
• use the letter from the input for your alphabetically ordered list as an key for
filtering or scrolling down

• here is an example with the translation collection to import into your
project 

17

Resources
• Natural Dialog Management.pdf

• VoiceObjects Help

18

Pavel Růžička
Programmer – Analyst
Service Development Department
T-Mobile Czech Republic a.s.
Tomíčkova 2144/1, 149 00 Praha 4
T-Mobile: +420 603 416 974
E-Mail: pavel.ruzicka@t-mobile.cz

19

Make a shorter list by entering letters via DTMF

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Make a shorter list by entering letters via DTMF