What can we help you with?

Any unanswered questions, please contact us. We’re happy to help.

What is Watertight?

Watertight is an enclosure method that provides a high degree of protection against the entry of water during temporary submersion.

Enclosures with a Type 4X & IP66 rating are constructed for either indoor or outdoor applications providing a degree of protection against splashing water, seepage of water, falling or hose directed water and severe external condensation. They are corrosion and sleet resistant but not sleet or ice proof.

Conduit hubs or equivalent are required for watertight connection at the conduit entrance and mounting means external to the equipment cavity.

Guardian Telecom’s Knowledge Base provides a description of Enclosure Ratings including Guardian Telecom Enclosure Types & NEMA enclosure types.

Are Guardian Weather Resistant telephones still weather resistant if the door is left open?

It happens. Even when the enclosure is built of rugged engineered polymer and industrial strength components, a door can inadvertently come off, be left open or damaged.

While Guardian’s weather resistant telephones are constructed to stand up to outdoor climates even without their doors, they are an essential component of the protection package and should be replaced as soon as possible.

Are support and parts available for discontinued products?

Service and parts are generally available for a 2 year period after a product has been discontinued unless it was discontinued due to availability of parts.

If you have additional questions contact Guardian Telecom.

Is mounting hardware included?

Mounting hardware is left to the discretion of the user as we cannot foresee the different environmental factors and applications that would affect the type and size.

Can I self-repair my phone?

All non-hazardous and some hazardous area, Class I Division 2 and Class II Division 1 telephones can be field repaired by the user. Refer to user manuals for the specific model.

Repairing an explosion proof (Class I Division 1) area telephone by a non-certified Guardian Technician will void the warranty, can make the equipment dangerous to use and can place lives at risk.

How Weather Resistant are Guardian telephones?

Guardian Weather Resistant telephones meet or exceed the requirements of the classifications for which the telephones are registered. These standards are set by various independent agencies such as the Canadian Standards Association (CSA), Underwriters Laboratories (UL) and International Electrotechnical Commission (IEC).

Guardian Weather Resistant Telephones are housed in a Type 3R enclosure for use outdoors and feature encapsulated circuitry impervious to water condensation and dust.

Guardian Telecom’s Knowledge Base provides a description of Enclosure Ratings including Guardian Telecom Enclosure Types & NEMA enclosure types.

What is Weather Resistant?

Weather Resistant is an enclosure method that provides a high degree of protection from rain, snow, windblown dust, splashing and hose-directed water and is undamaged by external formation of ice.

“This type of enclosure provides a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow); and that will be undamaged by the external formation of ice on the enclosure.” 1

1Modified from a statement from the National Electrical Manufacturers Association Approved by NEMA Enclosures Section 1300 N. 17th Street, Suite 1752 Nov 2005 Rosslyn, VA 2220920, Nov. 2005

Guardian Telecom’s Knowledge Base provides a description of Enclosure Ratings including Guardian Telecom Enclosure Types & NEMA enclosure types.

What is Explosion Proof?

Explosion proof is essentially low tech. A great deal of the safety of explosion proof technology rests in the brute strength designed into the enclosure. Guardian’s EXT-401 Explosion Proof Telephone is housed in a flame-proof enclosure of cast, copper-free aluminum.

The enclosure has openings for wiring to pass through. Each opening is designed and constructed to block the passage of any gases from the interior. Similarly, the back plate is sealed and secured to maintain the explosion proof nature of the housing.

While it is unlikely, if the telephone’s operation or a fault were to create an arc or spark in the enclosure and ignite gases or vapors within the phone, any detonation is contained in the housing. Should gases escape they are cooled sufficiently that they are relatively harmless by the time they reach the outside.

Performance and features are not compromised due to the design of the telephone which operates at normal telephone voltages.

What does intrinsically safe mean?

Intrinsically safe equipment is designed so that under normal operating conditions, or in the event of a fault, a spark or arc is incapable of causing an ignition of gases, vapors, or dust due to lower electrical energy.

One of the major features of intrinsically safe technology is that it relies on lower voltage/current in order to prevent arcing or sparking.

An important consequence of reduced voltage is that intrinsically safe equipment is constrained by these lower voltages. This means that some features must be eliminated and performance is reduced.

What is a Hazardous Area?

Hazardous locations are defined as places where concentrations of flammable gases, vapors, or dusts occur. Electrical equipment that is installed in hazardous locations are designed and tested to ensure that it does not initiate an explosion, due to arcing contacts or high surface temperature of the equipment.

Guardian Telecom’s Knowledge Base provides general information on ATEX Hazardous Areas & Hazardous and Classified Locations.

What do the Hazardous Area classifications mean?

Various standards and regulatory bodies establish classifications in North America, Europe and other jurisdictions around the world. They reflect environmental conditions and elements within that environment.

For General Information on Hazardous Areas Classes, Groups & Divisions (ATEX, NEC, CEC, IEC) go to Guardian Telecom’s Knowledge Base.

What does non-incendive mean?

Non-incendive technology relies on design and construction to produce a piece of equipment that performs safely and effectively without arcing or sparking.

A non-incendive telephone’s components are designed so that under normal operating conditions or in the event of a fault they are incapable of igniting vapors or gases that maybe present.

What is the reason for an explosion proof telephone?

Simply put, explosion proof apparatuses including Telephones, Page/Talk Stations, Talk/Back Stations, Loudspeakers and Ringers are used to protect lives and property in hazardous locations (Class I Division 1 and Class II Division 1 areas).

The design and strength of the enclosure of an explosion proof apparatus controls ingress and egress of a substance’s ability to enter or exit it.

For a fire to start there has to be three elements present – oxygen, heat and fuel. A small spark in a confined room, vessel, building or area where combustible dust particles are present in sufficient quantities and concentration can lead to rapid combustion.

“These five factors (oxygen, heat, fuel, dispersion, and confinement) are known as the “Dust Explosion Pentagon”. If one element of the pentagon is missing, an explosion cannot occur.” – OSHA Fact Sheet, March, 2008

Throughout the world Standard Development Organizations (SDOs) including the National Fire Protection Agency (NFPA) and National Electrical Manufacturers Association (NEMA) work to formulate health and safety standards from electrical codes (NEC) and standards to test methods and product specifications.

Governments in turn have passed laws requiring strict adherence to these codes and standards within their jurisdiction.

Guardian’s EXT-401 Explosion Proof Telephone, CE20 Ringer, SR40/SR60 Speaker/Ringer, EXP & EXP-A Page/Talk Stations, EXP-TBA Talk/Back Stations and OEM Loudspeakers are all designed to operate on standard telephone voltage while containing internal detonations if they occur and keep combustible elements out.

Is a handset the only method of using the EXT-401 Explosion Proof Telephone?

Guardian offers an aviator style headset with a built-in microphone and hand-controlled hook switch.

Are there other methods of telephone signaling to deal with a high noise environment?

Sound, visual or a combination of the two, provide viable methods for signaling within high noise environments.

Guardian designs and manufacturers our own high quality, rugged and reliable loudspeakers and ringers as well as distributing 3rd party strobe lights, loudspeakers and ringers from leading manufacturers. Hazardous area approved models are also available.

  • SR40/SR60 Explosion Proof Loudspeaker, Ringer & Loudspeaker/Ringer
  • CE20 Line Powered Ringer
  • CE20 Line Powered Ringer with horn
What can be done to improve telephone service in a noisy environment?

Dealing with noise is a progression. Noise reduction is standard on all of Guardian’s telephones.

All Guardian Telecom telephones can be equipped with noise cancelling microphones. (The EXT-401 Explosion Proof Telephone is the only exception.)

The next step is volume adjustment. Several methods are available depending on the telephone model.

  • Adjustment by buttons on a membrane key pad
  • Adjustment by volume up and down switch on a handset
  • The EXT-401 has a volume control button option.

If noise levels still make it difficult the final step is an Acoustic Booth. Guardian has a selection of AB-100 or AB-1000 models with up to -25 dB of sound deadening capabilities depending on the interior liner type.

Why does the EXT-401 Explosion Proof Telephone require an external signal?

The nature of the EXT-401 explosion proof enclosure with its thick, sealed copper free aluminum walls makes it impractical to effectively transmit sound from the inside of the enclosure.

Guardian Telecom offers a variety of options including the CE20 line-powered ringer, configurations of the SR40 Speaker/Tone Ringer and hazardous area strobes.

Is a handset the only method of using the EXT-401 Explosion Proof Telephone?

Guardian offers an aviator style headset with a built-in microphone and a hand-controlled hook switch.

Refer to applicable operation & install manual

Guardian telephones and accessories are thoroughly tested before shipment. Considering their construction it is unlikely the equipment will be damaged during shipment.

If the external equipment packaging appears damaged, the matter must be reported to the freight carrier.

Contact Guardian Telecom when a Class I, Division 1telephone fails to perform according to specifications. There are no user-serviceable parts so leave the enclosure sealed.

This is particularly important with safety rated equipment. Opening the enclosure of a Class I, Division 1 telephone or accessory cancels the safety approval and voids the telephone’s warranty.

If the enclosure of a Class I, Division 1 telephone or related accessories has been opened, the unit is no longer safe and must be removed from the hazardous area.

Manuals can be downloaded from individual Product web pages.

Incorrect Power Source

By far the most common problem is connecting the telephone to the wrong power supply. All telephones are to be connected to the telephone line. This line is not the same as standard building power of 120 volts.

If the telephone has been incorrectly connected, disconnect the line and consult the installation manual, sent with the phone, for proper connection instructions.

The manual also provides instructions on changing the telephone’s fuse.

Distance from Switch

If the telephone reception is very weak or the phone functions intermittently, it is likely that the unit has been installed too far from the switch (private branch exchange/PBX) or too many extensions have been installed on the line.

A maximum of five telephones may be installed on one line and the maximum distance from the switch to the telephone is 4.5 kilometres or 10,000 feet.

If more than five telephones have been installed on the line, the excess must be removed. Where the telephone is beyond the permitted distance, the unit must be installed closer to the switch or a power booster installed between the telephone and the switch.

Telephone Will Not Hang Up

In order to reduce the number of moving parts, subject to wear or damage, Guardian telephones are equipped with a magnetic reed hook switch.

a. Model EXT-401

The EXT-401 contains a magnet midway between the ear and mouthpiece of the hand set. If the phone will not hang up, be sure the handset is fully in place on the cradle.

On occasion the hook switch may jam; passing a magnet across the top of the handset cradle should correct the problem. If the problem persists, follow the Return Materials Authorization procedure.

b. Other Models

Other Guardian models, such as the WRT, SCT and WTT series contain magnets in the handset ear piece. If the handset is fully in place in the cradle and the phone remains off-hook, pass a magnet through the cradle. The hook switch should reset.

It is possible for the problem to be corrected and reoccur. Should this happen, the ear piece may be defective and should be returned following the Return Materials Authorization procedure.

What is the Warranty coverage?

Guardian Telecom will repair or replace any defective unit that is under warranty.

This warranty covers bench repairs only; such repairs must be made at Guardian Telecom or an authorized service depot.

Guardian Telecom is not responsible for costs incurred for on-site service calls, freight, or brokerage.

This warranty is null and void if any non-authorized modifications have been made to this product, or if it has been subjected to misuse, neglect, or accident.

A return authorization must be obtained prior to warranty claims or repairs.

How long is the Warranty period?

Three years.

When does a Warranty go into effect?

A Warranty goes into effect from date of invoice.

Are Guardian Hazardous Area telephones field serviceable?

Hazardous Area Class I Division 2 and Class II Division 1 telephones are field serviceable.

Explosion proof telephones are not field serviceable. Maintaining the safety approvals require an authorized technician to service Explosion Proof area telephones.

For instance, in the case of the EXT-401, its ability to contain an internal explosion is based solely on the integrity of the enclosure. Therefore, the back panel of the telephone must be properly attached after being removed.

What actions may null and void a warranty?

This warranty is null and void if:

  • Any non-authorized modifications have been made to this product, or if it has been subjected to misuse, neglect, or accident.
  • If the equipment has been installed improperly and instructions have not been followed.
Can all equipment be Field Repaired?

Field repairs may only be carried out on equipment that has been identified as field serviceable. If uncertain whether your product falls in that category you must check the product label or contact Guardian Telecom before proceeding.

Field repairs may only be carried out by qualified technicians using OEM parts

Substitution of parts voids warranty and may pose a hazard to users of the equipment.

What should I do if, without authority, someone opens the enclosure of a hazardous area telephone or accessory?

In all instances, refer to the user manual for the Explosion Proof device you are installing or contact Guardian Telecom immediately for assistance.

Manuals can be downloaded from individual Product web pages.

Opening the enclosure of the Explosion Proof area telephone has voided safety approvals; can I still use the telephone?

The telephone must be removed from the Class I, Division 1 hazardous area because it is unsafe. It can probably be repaired and receive a new safety certification, however, that requires the telephone be returned to Guardian.

What steps must be followed to have a telephone repaired?

Guardian Telecom repairs all of its telephones and accessories.

The following links provide information to help ensure timely and effective repairs directly at the Guardian Telecom manufacturing facility or an authorized repair depot.

Still need RMA help?

Call 1-800-363-8010 (toll free in North America), 1-403-258-3100 and ask to speak with the RMA department or send an e-mail to

How do I update my firmware?

Download and extract the firmware file for your VoIP product type.

XML Sample Script & Firmware – Handset-IP Models

XML Sample Script & Firmware – HDE-IP Models

Then follow the instructions in the related Setup & Configuration Manual to your product type.

VoIP Telephone Setup & Configuration for Handset Models

VoIP Telephone Setup & Configuration for HDE Models (hands-free)

Who should I contact for additional support or answers to questions not covered here?

The first step is to fill out and submit the linked VoIP Help Desk Request Form which will help to define the issue and gather all pertinent information needed to expedite the process.

Contact Guardian Telecom if one-on-one technical help is required.

When dialing the three-digit DTMF tone on the IP phone, I can hear the DTMF-tones coming out of the speaker of the VoIP device but there is no relay action. The relay works when using the relay test-button on the configuration software. How do I fix this?

Since the relay test button is working, it seems like the problem results from interfacing with the IP phone where the DTMF tone is generated. To resolve this problem verify that the DTMF tone on the phone is set to out-of-band.

I was able to register your device with our SIP server, but when I tried to enter a DTMF tone there was no function.

Make sure your SIP phone is set to 101 for the DTMF payload type (Out of Band RFC2833).

After a period of time, my device stops working or is unreachable.

This is a common problem when the re-registration time value is not set correctly.

On a Guardian VoIP device, you need to make sure that the re-registration time value (in minutes) is less than that is set on the IP-PBX server.

On an Asterisk-based VoIP SIP PBX system, the Guardian SIP Device status is “Busy” or “Unreachable”. I have set up both the Guardian VoIP SIP device and the PBX extension information for the device. I can see the device on the network, am able to PING it, and can bring up the device web page with a browser. However, when I try to call it from a phone extension, I see the word “Busy” or “Unreachable” in the Asterisk log.

In the PBX setup page for the extension of the Guardian device, find the Qualify= value and change it to NO. If the Qualify= value requires a numeric value, then change it to 0.

Note that on some Asterisk systems (such as Intuitive Voice) this value is called the Heartbeat= value. Set the Heartbeat= value to NO, and then save the settings.

Also, on the product’s SIP Setup page, make sure that the Register Expiration (minutes) setting is set to less than 6minutes (5 minutes is good) because it needs to be a value less than the Asterisk default value of 6 minutes. Save the settings, after changing the Register Expiration (minutes) setting.

What type of audio files can be uploaded into the device?

RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono 8000 Hz

You can use the free utility ‘Audacity’ ( to convert audio files into a format the device can recognize.

When you export an audio file with this program, you can save the output as “WAV (Microsoft) signed 16 bit PCM.”

What happens during a firmware upload if the process gets corrupted?

Guardian Telecom VoIP units feature a built-in “fail safe” mechanism.

The Device will store the “TFTP Server IP” and “New Filename” entered on the “Update Firmware” web page. If, during the boot process, the Device is unable to boot the firmware, it will attempt to download the stored image from the stored TFTP server.

I see in the electrical connection diagram in the user’s guide that there is a High PIV Ultra Fast switching diode. Do I need it and if so do you have a source?

This High PIV Ultra Fast switching diode prevents CEMF kick back from an intermediary relay coil when power is cut and the coil field collapses. You could use an On-Semi MUR105 diode or an IN4007, which is readily available.


Digi-Key Part Ordering (Supplier)

We have the Cisco 3550 switch and it looks like the unit is not able to negotiate the power with the switch. It keeps cycling over and over.

This happens because with default settings, the switch port is resetting power too quickly. Therefore, on the 3550 switch, on the switch port that the unit is attached to, please try adding the following CLI command:

  • power inline delay shutdown 20 initial 300

That should keep power supplied until the unit can boot up all the way.

The Guardian device connected to a Dell Powerconnect 3524P or 3548P port did not stay linked up. The device comes up, and then it goes down, and then it comes up cycling.

If connected to a Linksys SRW208MP switch, the Guardian device stays up.

Pantel, Cisco, or Linksys PoE endpoints all work on the Dell Powerconnect 3524P.

A user tried hard coding the switch speed/duplex and tried four different Dell Powerconnect 3524P switches. — Check to make sure the Dell Powerconnect 3524P has flow control enabled on the port for the Guardian device to power up properly.

I am unable to connect with the unit when it is plugged into a Cisco SLM 224P switch.

According to Dell:

Flow Control Support (IEEE 802.3X): Flow control enables lower speed devices to communicate with higher speed devices by requesting that the higher speed device refrains from sending packets. Transmissions are temporarily halted to prevent buffer overflows. For information on configuring Flow Control for ports or LAGs, see “Defining Port Configuration” or “Defining LAG Parameters” in the Dell™ PowerConnect™ 35xx Systems User’s Guide.

Change to MDI:

MDI / MDIX ­ displays the Media Dependent Interface (MDI) / Media Dependent Interface with Crossover (MDIX) status on the port. Hubs and switches are deliberately wired the opposite of the way end stations are wired, so that when a hub or switch is connected to an end station, a straight through Ethernet cable can be used, and the pairs are matched up properly. When two hubs or switches are connected to each other, or two end stations are connected to each other, a crossover cable is used to ensure that the correct pairs are connected. The possible field values are: – MDIX ­ Use for hubs and switches. – MDI ­ Use for end stations.

I have a Cisco 6513 switch. When I plug in a Guardian VoIP device, the device constantly reboots and will not register to the SIP server.

Adjust the switch power selection to Power inline static, as opposed to Power inline dynamic. This will allow the device to continuously receive 15.4W of power.

We have registered the device on Cisco Call Manager but are unable to register the device’s Nightringer using the device’s MAC address. How do I configure two extensions on Call Manager for the device?

Create a second directory number and user for the Nightringer extension. You may need to fudge a digit of the MAC Address so that Call Manager allows you to associate it to the new user.

Be sure this MAC address does not match any other Guardian devices on your network.

Contact Us

We're not around right now. But you can send us an email and we'll get back to you, asap.

Not readable? Change text. captcha txt

Start typing and press Enter to search products