Hummer H2. Manual - part 224

analog (Generation 5) or digital (Generation 6) cellular tower, the state of the cellular carriers' equipment, and 
the location where the call is placed. Making an OnStar(R) keypress in areas that lack sufficient cellular 
coverage or have a temporary equipment failure will result in either the inability of a call to complete with a 
data transfer or the complete inability to connect to the OnStar(R) Call Center. The OnStar(R) system may also 
experience connection issues if the identification numbers for the module, station identification number (STID) 
and electronic serial number (ESN), are not recognized by the cellular carriers local signal receiving towers. 
OnStar(R) cellular connection issues such as these require the assistance of the General Motors Technical 
Assistance Center OnStar(R) Group, which coordinates with cellular carriers to resolve connection issues. 

The satellites that orbit earth providing the OnStar system with GPS data have almost no failures associated 
with them. In the event of a no GPS concern, the failure will likely lie with the inability of the system to gain 
GPS signals because of its location, i.e. in a parking structure, hardware failure, or being mistaken with an 
OnStar(R) call which has reached the Call Center without vehicle data. 

During diagnostic testing of the OnStar(R) system, the technician should ensure the vehicle is located in an area 
that has a clear unobstructed view of the open sky, and preferably, an area where analog (Generation 5) or 
digital (Generation 6) cellular calls have been successfully placed. These areas can be found by successfully 
making an OnStar(R) keypress in a known good OnStar(R) equipped vehicle and confirming success with the 
OnStar(R) Call Center advisor. Such places can be used as a permanent reference for future OnStar(R) testing. 

OnStar(R) Personal Calling 

The hand free, OnStar(R) personal calling (OPC) cellular phone feature is an additional option to the OnStar(R) 
system. This feature is already embedded within the vehicle communication interface module (VCIM), 
however, it must be activated by an OnStar(R) advisor. This is done most often during the initial OnStar(R) 
configuration, if the home location of the vehicle is in a geographic area where OnStar(R) personal calling is 
available. In the event this feature is not enabled, customers may connect to the OnStar(R) Call Center by 
pressing the blue OnStar(R) button, and asking an advisor if OPC is available in their area. Users of the 
Generation 5 or Generation 6 OnStar(R) system can verify the system has been configured for OnStar(R) 
Personal Calling by pressing the answer/end call button, waiting for the system to respond "OnStar Ready" then 
speaking the word "dial." If the system responds with a failure message, the system has not been configured for 
OPC. All other responses confirm that OPC has been enabled. 

Operation of the Hands Free Cellular Phone 

Onstar(R) personal calling (OPC) operates similar to most hand held cellular phones in that the availability for 
its usage is based on minutes or units. The customer must have a current OnStar(R) subscription, as this feature 
cannot be utilized without it. To use OPC, the customer must also purchase units as outlined in the owners 
guide provided with the OnStar(R) system. When the customer purchases minutes, an OnStar(R) advisor loads 
these minutes into the vehicle communication interface module (VCIM) over the airwaves at the time of the 
request, or through a discrete cellular call to the vehicle at a later time. Once loaded into the module, the units 
may be used for non-international, outbound cellular phone calls, and connection with the OnStar(R) virtual 
advisor. Units begin to deplete, one unit is equal to one minute, as the customer makes outbound phone calls, 
answers inbound phone calls, or while connected to the OnStar(R) virtual advisor. In addition, units also have 
an expiration date, depending upon the type of units purchased. This date is established when the download is 
performed, and any remaining units expire when the date within the VCIM, which is based on current date and 
the time transmitted by global positioning system (GPS) satellites, has passed. At any time, the user can press 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Cellular Communication - Hummer H2

  

the answer/end call button, say "Units" and verify the number of units remaining.

During a hands free call, the microphone and audio system operate the same way as a standard OnStar(R) call. 
When the answer/end call button is pressed, the audio system will mute; the OnStar(R) system will then return 
the prompt "OnStar Ready." At this point there are specific commands set to initiate a cellular call. If the 
vehicle receives a call when the radio is ON, the audio system will mute and an audible ring will be heard 
though the speakers. The call will be answered when the answer/end call button is pressed. 

The VCIM interprets all of the voice-activated commands. A complete list of these commands is supplied in the 
information provided to the customer. If the information is not available to reference, at any command prompt 
the caller can say "HELP" and the VCIM will return an audible list of available commands. If the customer 
concern is not being understood or not being heard by the OnStar(R) system, the user should place a call to the 
OnStar(R) call center to verify proper operation of the microphone. Following this description is an example of 
the commands and the OnStar(R) system responses. A complete list of commands is supplied in the information 
provided to the customer with the OnStar(R) system. 

OnStar(R) Steering Wheel Controls 

Some vehicles equipped with the OnStar(R) system have the capability of accessing voice mailboxes and other 
automated phone systems by means of the steering wheel controls, while the OnStar(R) personal calling (OPC) 
feature is in use. If the Talk or Mute button, depending upon the vehicle, on the steering wheel controls are 
depressed during an OPC call, the vehicle communication module (VCIM) receives the message on the class 2 
serial data bus from either the radio, the driver information module, or the body control module (BCM). This 
message is interpreted as a request to turn any spoken numbers into dual tone multi-frequency (DTMF) tones to 
be delivered over the airwaves to the phone system the user is communicating with. Complete instructions for 
operation of these features can be found in the information provided to the customer with the OnStar(R) system.

The steering wheel controls are a resistor network that consist of multiple momentary contact switches and a 
series of resistors. The switches and resistor network are arranged so that each switch has a different resistance 
value. When a switch is pressed, a voltage drop occurs in the resistor network, which produces a specific 
voltage value unique to the switch selected, to be interpreted by either the radio, driver information module, or 
body control module. 

OPC Features 

The following is an abbreviated list of features that may have an impact for the technician when servicing or 
diagnosing an OnStar(R) system. For a full list of OnStar(R) Personal Calling features, consult the owner's 
guide provided to the customer with the OnStar(R) system. 

Voice Feedback 

The OnStar(R) personal calling (OPC) system has the capability of responding to the user with either an 
automated voice response or with a tone or beep. These 2 types of responses can be switched back and forth by 
pressing the answer/end call button, waiting for the system to respond "OnStar Ready" and speaking the phrase 
"voice feedback." The system will then respond, "voice feedback is now on/off." 

OPC Security/System Lock 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Cellular Communication - Hummer H2

  

Customers have the capability to lock their OnStar(R) personal calling (OPC) system by pressing the 
answer/end call button, speaking "security" and entering a 4-digit code. Once this process is complete, the user 
must enter the code before OnStar(R) personal calling is available. In the event the customer cannot remember 
their code and is unable to use their system, they can press the blue OnStar button and speak to an advisor to 
unlock the system by means of a discrete cellular call to the vehicle. 

Nametags 

Customers have the ability to store telephone numbers within the module, referenced by a nametag for the 
convenience of frequently dialed numbers. This process is initiated by pressing the answer/end call button, 
waiting for the system response, then speaking the response "store". The system will respond with "number 
please" at which time the user should enter the number desired to be stored. Once complete, saying the word 
"store" again lets the system know you are finished entering the number. At this time, the system will elicit the 
user to assign a nametag to that number. From this point forward, the user can dial this number by initiating the 
OnStar(R) personal calling (OPC) feature, speaking the word "call," and repeating the nametag assigned. To 
delete a nametag, the user should initiate OPC, say "delete" then speak the nametag to be removed. In the event 
a nametag cannot be deleted in spite of repeated attempts from several speakers, the OnStar(R) module will 
require replacement. 

Mobile Identification Number and Mobile Directory Number 

The Generation 5 and Generation 6 vehicle communication interface modules (VCIM) utilize 2 numbers for 
cellular device identification, call routing and connection, a mobile identification number (MIN) and a mobile 
directory number (MDN). The MIN represents the number used by the cellular carrier for call routing purposes 
while the MDN represents the number dialed to reach the cellular devise. Although technicians have the 
capability to change these numbers by means of the scan tool, this should ONLY be done at the direction of and 
with explicit instruction from General Motors Technical Assistance Center (GM TAC). 

Dialing a Phone Number Hands Free (Generation 5) 

Placing a Call (Generation 6) 

To Dial a Number 

Caller Action

OnStar(R) System Response

IMPORTANT:

If you make a mistake with a number or the OnStar(R) system misunderstands you, say "clear." This 
will erase the last number said.

Press the Answer/End Call button.

"OnStar Ready"

Dial

"Number please"

Say each number clearly, pausing until the 
system confirms receipt of the number. 
With Generation 6, OnStar will understand 
all digits spoken continuously, without the 
pauses and repetition in between.

The system will repeat the number stated. If the number 
was not heard or understood, the system will state the 
word "number" prompting the user to repeat the last 
number.

Dial

"Dialing" or "Dialing" plus the phone number given

What You Do

What You Hear

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Cellular Communication - Hummer H2

  

After 3 unsuccessful tries, or if you simply like it better, you can use the "Digit Dial" command to input digits 
one at a time. Digit Dial is set up to dial phone numbers like previous OnStar Personal Calling Systems 
(Generation 5). 

To Dial a Number Using Digit Dial 

To Place a Call Using a Stored Nametag 

To Place a Call Using the "Redial" Command  

Operation of the OnStar(R) Speech Recognition Systems 

OnStar(R) Generation 5 and Generation 6 users communicate with 2 speech recognition systems. Speech 
recognition allows the user to speak to one computer in the vehicle, and one reached over a phone line. The 
computer tries to understand the user's command, and responds by speaking back, or by taking the appropriate 
action, e.g. dialing the phone. 

z

Personal Calling uses a speech recognition system that resides in the vehicle. When the user presses the 
dot button, the system states, Ready, and listens for the user's command. The user can speak commands to 
control the hands-free phone.  

z

Virtual advisor is a remote speech recognition system that the caller access by making a phone call. The 
user connects to virtual advisor by requesting it during personal calling use. The user is then transferred 
to the virtual advisor server and talks to it via a cellular connection. 

Press the white dot button

"OnStar Ready"

Say "Dial"

"Phone number to dial, please"

Say the entire phone number you wish to dial with no 

pauses

OnStar will repeat the number, then ask "Yes 

or No"

Say "Yes" if the phone number was correct, or "No" to 

try again

"Dialing," and your call will be connected

What You Do

What You Hear

Press the white dot button

"OnStar Ready"

Say "Digit Dial"

"First digit to dial, please"

Say the number to be dialed, one digit at a 

time

OnStar will confirm each digit by repeating it back to 

you

When finished, say "Dial" again

"Dialing," and your call will be connected

What You Do

What You Hear

Press the white dot button

"OnStar Ready"

Say "Call"

"Nametag, please"

Say (stored name)

"Calling"

What You Do

What You Hear

Press the white dot button

"OnStar Ready"

Say "Redial"

"Redialing"

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Cellular Communication - Hummer H2