Category Archives: GSM Blog

What’s new in July

We ended June having brought our new Gold G2 2-Button Intercom into full production and having restocked our old 1-Button internal aerial unit.

GSM Intercom

Advent Controls G2 Intercom

We have a new PCB which will form the basis of all of our dialers and gate/shutter openers going forward.  It features an ultra-low power mode, more inputs and outputs, space for a voice unit and Bluetooth.  The chip on the PCB has a larger program memory (like the hard drive of a PCB) giving us space to add more features.  The power supply design is more rugged too allowing for higher voltages and better surge protection.


GSM Roller Shutter Controller

We’ve finally given up on the Circuit Switched Data (CSD) system we used for remotely connecting to devices in the field and have revised the software to use the GPRS packet data system.  We chose CSD as it meant your SIM did not require data and there was no need to tell the GSM unit your network’s APN (Access Point Name) e.g.…  The problem is CSD does not really work at all never mind reliably.  Quectel have dropped support on the new modems we are using so it was time to switch to GPRS.

GSM assembly code

We’ll be using GPRS to dial in in future

There are huge benefits though.  The newer PCBs including our Gold G2 Intercom can have a full firmware update over the internet using GPRS.  We have also added the ability for the dialers and gate openers to send emails whenever activity is detected.  Eventually we will either offer our software to the end user or create a web interface for setup to be done online.

Setup GSM dialers and intercom online

Advent Controls Web Interface Software

New features – feedback definitely welcome!!

  • Dial, SMS and email
  • Bluetooth Setup
  • Low power modes
  • PC interface software
  • Ability to email list of settings and stored numbers
  • 2-In, 2-out PCB due August
  • Keep Alive text to display balance

Michael Beaver, Director


Vodafone Dialing Issues 24/07/15

!!Please note this has been resolved by Vodafone (31/07/15).  We would recommend testing your alarm however!!

Last week we were notified by an installer that he was unable to get the dialer to dial mobile numbers using a Vodafone SIM; texting was unaffected.  We replaced the SIM card in the unit for an EE based reseller (Vectone) and the dialer functioned perfectly.

After investigating the cause, we found Vodafone have started to mis-report the call status of an out-bound call (more information below).  The simple resolution is to use an O2 or EE based SIM provider.  We updated the firmware to allow Vodafone to be used, as is, but with some additional commands required:

divert en

With Diverts Enabled the call length is now set by (without divert en it defaults to 5s):

ctime xx.  (the default is 58 seconds)

If you are using a Vodafone SIM in your dialer, run an alarm test to see if your local cell is affected by the issue.  If it is, ensure you have SMS alerts (textnum xxxxxxxx.) set up along with calling alerts.  You will require firmware F3.15 or later for ‘divert enable’ to be effective.

The Issue

To understand the issue we need to look at the information we obtain about the call from the network using the AT+CLCC command.  This command reports back the call status.  Here is an example of how a call is handled using the Vectone EE network SIM:

..+CLCC: 1,0,2,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,2,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,2,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,2,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,2,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,2,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,3,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,3,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,3,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,3,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,0,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,0,0,0,”07930666555″,129,””….OK..
..+CLCC: 1,0,0,0,0,”07930666555″,129,””….OK..

The CLCC data is checked every second.  When the dialer is triggered we see the status of the call goes to status 2 (highlighted in red) which is the ‘DIALING’ phase.  This is the time when the call is set up with the network.  After 6 seconds we see the next CLCC report shows the call is now at status 3 ‘ALERTING’ indicating the remote phone is ringing – at this stage the recipient can hear the phone ringing.  When the phone is answered, we see the call goes to status 0; the ‘ACTIVE’ state.  This means the phone has been answered.

Finally, after 3 seconds the call is ended by the recipient and we see ‘NO CARRIER’ is sent by the network.  This is an example of how a call should be handled.

..+CLCC: 1,0,2,0,0,”07830666575″,129,””….OK..
..+CLCC: 1,0,2,0,0,”07830666575″,129,””….OK..
..+CLCC: 1,0,2,0,0,”07830666575″,129,””….OK..
..+CLCC: 1,0,2,0,0,”07830666575″,129,””….OK..
..+CLCC: 1,0,2,0,0,”07830666575″,129,””….OK..
..+CLCC: 1,0,0,0,0,”07830666575″,129,””….OK…
..+CLCC: 1,0,2,0,0,”01517283167″,129,””….OK..

Above shows how Vodafone have been reporting a Mobile Originated (MO) call since the issue arose.  As before we see the call immediately going to status 2 after a dial command as expected.  However, prior to when the recipient’s phone starts to ring the status of the call is reported at status 0.  When a call goes from status 2 to 0, this is indicative of a call going to voicemail.  Voicemail does not ring out and it is diverted without the ringing phase hence the dialer moves on to the next number as we can see.

This can occur normally with Vodafone as they play a voice message telling the caller to top up credit when credit is low.  However, this behaviour has started to happen on all calls no matter what credit is available and causing the dialer to skip all calls.

The command ‘divert enable’ allows calls to go to a diverted number.  Normally you would not want this as there is no point calling voicemail with the dialer.  However, as there is no accurate way of detecting the status of a call with this Vodafone issue ‘divert enable’ will allow the call to continue.  This command was originally intended for our intercoms to allow mis-resporting (it occasionally happened with some MVNOs like Lyca Mobile) but must be used on an affected Vodafone SIM.

As the length of an alarm dialer call is limited to 5s this is insufficient time for a mobile call to be set up.  Therefore, the firmware we released this week (29/07/15 F3.15) allows the CTIME command to set the length of the call when diverts are enabled.


Hopefully this network issue will be resolved shortly by Vodafone.  If this persists and Vodafone is the only available network, we recommend returning the dialer to Advent Controls for a firmware upgrade.  Our latest firmware release allows any future updates to be performed over the internet using GPRS.

Dialer Information Page

Friedland Response SA5 Alarm connection to GSM Auto Dialer and SMS Sender

Response SA5 GSM Dialer Wiring Connection using Relay

GSM Dialer Connection using Relay

There are 3 ways of connecting the Advent Controls GSM Alarm Dialer to the Friedland Response SA5/SL5 Wireless Alarm panel.  The easiest way is to make use of the output relay on the internal wiring connection header within the Response panel.  By connecting the GSM dialer’s input to the GND terminal through the alarm’s relay NO (Normally Open) and C (Common) terminals the dialer will start calling and sending SMS messages.

Response SA5 GSM Dialer Wiring

Connection using the wired bell output

When using the relay the panel must be programmed to output a signal using the relay when the alarm sounds.  The following is taken from the manual

Relay settings for connecting the Reponse SL5 Burglar Alarm to a GSM Dialer

Response SL5 Relay Config

Setting the relay to 2s if sufficient.  Thanks to Ray Dunne for the information

The second way makes use of the 12v output designed to drive an external wired bell.  Unusually this terminal goes from a high impedance state to +12V when active (alarm sounding).  This is contrary to the requirements of most wired bells which normally are wired to an open collector transistor output which is pulled to 0v (negative edge) when active.

The dialer can be set to look for the positive edge using the following command:

inlevela open      (Firmware F3.11 and earlier) or,

inlevela positive (Firmware F3.12 and later)

As the output is high impedance when not active it will be pulled high by the dialer input source current.  Therefore a resistor should be wired between the Input A terminal and GND to keep the input at 0v when not active.  The resistor should be 470-2000 ohms.  A 470R resistor is normally included with the dialer for this purpose

Finally it is also possible to wire the integral voice dialer to the input as in the Yale alarm video.  When the alarm goes ‘off the hook’ to dial the numbers the GSM dialer sees a connection between input and GND triggering dialing using the GSM network.

The Advent Controls GSM Alarm Dialer is available here

GSM Gate Opener A3.02

Advent Controls A3.02

GSM Alarm Dialer Scantronic i-on i-on40 Compatibilty Question

Hi,Is this compatible with Scantronic i-40 bugler alarm?
How to wire a Scantronics alarm panel to the Advent Controls GSM Alarm Dialer

GSM Alarm Dialer to i-on40 Wiring

The dialer can be wired to this panel as Cooper Security recommend in their manual a wired bell box to be wired.  That is to make use of one of the output relays (OP1 in the diagram).  When using a relay you wire it in such a way that the input A or B is shorted to GND when the alarm sounds.  The diagram also shows power being derived from the panel.  The AUX 0V terminal goes straight to the GND terminal on the dialer and the 12V terminal goes to the lower VIN terminal on the dialer as this is the connection with the thermal fuse protection in case of accidental short circuit.

If there is no bell connect to your alarm then you will most likely find the TR terminal is already connected to 0v but if not ensure this is connected.  There are alternative ways to wire the unit, such as using the OP3/4 terminals but we would recommend following the advice in the manual.

GSM Dialer

GSM Alarm Auto-dialer

The Advent Controls GSM Alarm Dialer is available here on the Advent Controls website.

Scantronics i-on40 alarm wiring manual

GSM Dialer/Gate Opener Current Consumption Question

Hi there,
How many milliamps does it need from the alarm board to run?

(no name supplied)

GSM Dialer Current at various voltages

GSM Dialer Current Graph

As can be seen from the graph the current consumption drops with increasing supply voltage.  The is due to the use of an efficient Switch Mode Power Supply (SMPS) buck regulator on board which converts a high voltage at low current to the low voltage and high current required by the GSM transmitter chipset.  The GSM system requires up to 2 Amps at 3.6v.  However, due to the SMPS at 28v the current requirements during transmission are as low as 60mA average.  This can also be explained due to the 12.5% duty cycle used during GSM TDMA transmissions.  GSM transmits only in short powerful bursts with a 1/8th duty cycle.

The system’s electrical energy requirement every second (by definition this is know as Power) is the same whether the PCB is supplied by 12v, 18v or 28v.  Power consumption can be calculated for DC loads using the following formula:

Power  = Voltage x Current  normally written  P = VI

The inverse current plot is expected when we re-arrange the formula as follows:

I = P/V

As the power requirement, P, is constant no matter what voltage we supply we see as the voltage, V, is increased I, the current, must be reduced.

GSM Dialer power requirement

GSM Dialer Power Consumption

The above graph showing power consumption at various voltages shows the most efficient supply voltage is approximately 12v particularly when idling.

Please note these figures were obtained on the 1800MHz band (EE network) with a low RSSI of 10.  They were obtained during the higher power ringing phase and would drop during talk-time.  Transmission at 900MHz (O2 network) may give higher current consumption due to the higher power output of the transmitter but may also be lower if the signal strength is superior.
Here is the measured current consumption at various DC voltages:

20mA idle
60mA during call (peak 70mA with relay on)
26mA idle
95mA call (115ma Relay)
30mA Idle
110mA (145mA Relay)
127mA (160mA Relay)



The GSM Alarm Dialer and SMS sender is available from the Advent Controls website using the following link:

GSM Call List AT+CLCC Customer Question (it gets a bit technical!)


When I use my smartphone, the dialing screen turns green when the number I called answers,​ h​ow that’s accomplished? Do you know if your chipset has the hardware ability to determine when the call is connected, like via the gsm protocol stack?

​That​ can’t catch the automated voice messages from the phone company (like “the ​number you ​are calling ​is unreachable”) but it can eliminate the ringing tone and that would be sufficient.

DSP would be better but as you say it can’t be readily nor easily done.


GSM Intercom Question Reply

Ringing GSM Phone

[Note: the customer would like us to stop the 400Hz ringing tone from being audible during a call]

Hi <name>,

The network will tell you some things about the call but often (especially when you use a network reseller’s SIM card) it does not give accurate information.

For example, in the UK a company called Lyca resell the O2 network airtime. When using their SIMs the CLCC data in invalid. This is why we had to offer an option to turn off the voicemail divert command. Normally we detect voicemail diversion by noting when the phone does not ring. If the phone is switched off it will dial then instantly connect to the voicemail service which we can see happening from the CLCC command. We see it going to status 2 to 0 and never getting to 3 which is the ringing status. However, Lyca always show transition from 2 to 0 regardless of whether the phone rings or not and never give a status 3 when the phone is ringing. Basically the network notifications are unreliable.

Our intercom (available here) unit has a connection to the microprocessor from the audio circuit so we can digitize the audio and detect frequencies and whether there is audio or not. This is how we implement the SILENCE command functions.

We could switch the volume down to 0 during status 3 on a CLCC request but this may not work with some networks. That would be the easiest way to do what you require. I’ll look into it

Reply from AT+CLCC    NB:  <call state> is of interest here

+CLCC: <idx>,<dir>,<call state>, <mode>,<mpty>,<number>,<type>[,<alpha>] [<CR><LF>]

<state> 0 Disable CLCC unsolicited indication1 Enable CLCC unsolicited indication
<idx> Integer type, call identification number
<dir> 0 Mobile originated call (MO)1 Mobile terminated call (MT)
<call state> The state of the call0 Active1 Held

2 Dialing (MO call)

3 Alerting (MO call)

4 Incoming (MT call)

5 Waiting (MT call)

6 Released

<mode> Bearer/Teleservice0 Voice Call1 Data

2 Fax

<mpty> Multiparty status0 Call is not part of a multiparty call1 Call is one of multiparty call parties
<number> Phone number in the format specified by <type>. Contains a string of up to 32 characters.
<type> Phone number display format. Type of address octet in integer format (refer to GSM 04.08 [8] subclause 129 Local number






Michael Beaver


Yale HSA6400 Wireless Alarm connection to GSM Alarm Dialer

In the video Michael demonstrates the new Yale HSA compatible GSM dialer and SMS sender.

This is useful where there is no landline connection near the alarm or in the property.  It also gives additional information about individual sensor via email or SMS text.

The Advent Controls GSM Alarm Dialer is available here

SMS Power Fail

SMS Sender for power monitoring applications