Crux LX – Frequently Asked Questions (FAQs)

Crux LX is a plug-and-play device as it comes pre-configured for most common needs. It just needs to be powered on, and like any other Access Point (AP) or router, its wireless radio or SSID (as described on the box) is available for devices to connect. For it to connect to internet it needs a wired ethernet (RJ45) connector coming from your cable or fiber modem, as you would with any other AP or router. A quick reference guide is available for download from our website using which you can easily start distributing the 100 pre-configured extension numbers to users. For voice communication, Crux LX acts like a SIP server. To connect to this and start using voice, you could download any of the SIP client application or softphone application that allows you to input three key data points:
  • Extension number
  • Password
  • IP Address of Crux LX.

  • These three credentials allow a SIP client to register with Crux LX and you are ready to call one another!
    Each Crux LX unit can connect up to 250 users though one can configure thousands of extensions on a single unit, if the unit is being used only as an IP-PBX and not as a data router. Browsing needs and patterns can be very different, especially if audio visual content is permissible. The limiting factor however is the expected concurrency. Each Crux LX unit can support up to 20 concurrent conversations. However, you may require multiple Crux LX devices if you expect to connect more than 250 users or require more concurrency. You may also require some additional access points to span the space to connect large number of users who may have a mixed usage (Crux LX as well as regular browsing needs).
    Internet is not a requirement for Crux LX when operating autonomously, say for example when Crux LX is being used as a Wireless Intercom. However, when SIP trunks or multiple Crux LX devices are to be inter-networked to connect multiple branch offices, then internet will be required and quality / bandwidth of internet connection will be of importance. It will play a significant role in quality of voice and service delivered by Crux LX for communication over such channels. You may also require some additional networking components based on such use cases.
    You can fill up a brief questionnaire that will get the responses to Crux Labs. You will likely receive a response within 24 hours. Here’s the link to the questionnaire.
    Crux LX has a circular internal antenna. In our tests, beta trials and few customer deployments, the coverage ranges between 20 – 30 meters spherical radius. However, wireless signal can vary drastically based on construction and use of glass and metal. Typically scaling beyond one floor above or below, or 10,000 square feet of horizontal space will require additional Wireless Repeaters or Access Points. Crux LX pairs well with D-Link DIR-816 which is an inexpensive router (retails for $40-50) that works well as a repeater that provides good ground coverage and well suited for this use.
    Crux LX requires 2.5A, 5.1V over a Micro USB B type port. Crux LX is shipped with a Universal Power Supply 2.5A, 5.1V, Micro USB B, with a non-detachable 1.5m Cable.
    Most android mobile phone chargers may not suffice as the maximum power they support is typically 1A. Similar is true with battery banks. However, some battery banks or chargers that do provide a 2A / 2.5A port for fast charging and those can power up Crux LX unit too. At Crux Labs, we use a battery bank with a 2A port option for demo purposes all the time. A 5,000 mAh battery bank keeps Crux LX unit powered up for 6-8 hours, depending upon number of devices (GSM dongles, USB drives, etc) connected to it.
    • Does Crux LX support PSTN trunk (landlines)?
    Crux LX works in conjunction with various other devices and technologies. At this time, PSTN/POTS (Landline) interface with Crux LX is supported but not offered since the interfacing dongle we are currently dependent on is not cost effective. And, given that PSTN is an old technology soon to be overtaken by SIP, we have prioritized having SIP support along with GSM, that benefits more number of customers. Please get in touch with us at if you have a pressing need for PSTN/POTS support and are willing to shell out a few hundred bucks to get this support.  
    • Does Crux LX support GSM trunks?
    Crux LX can support multiple GSM trunks via a 3G to USB modem dongle. We have standardized on Huawei E1750 dongle as it supports simultaneous use of voice and data, and has undergone multi-tude of tests in the lab with Crux LX. You may directly procure the 3G modem or procure it from Crux Labs at a nominal cost of S$50 per dongle. If you wish to use the dongle for data only (not voice calling), then theoretically, any 3G dongle should work with Crux LX, though we do not have the means and access to test different dongles. We recommend use of Huawei E1750.  
    • Does Crux LX support SIP trunks?
    Crux LX can support multiple SIP trunks, from across the globe. We are in partnership conversations with SIP trunk providers across the globe. Please subscribe to our mailing list to stay tuned to updates. Currently, in US, we re-sell lines and shortly tying up with telcos in South East Asia region.
    Crux LX eliminates the need for additional instruments for voice communication. The easiest and convenient way is for users to use their Smart Phones (iOS or Android). However, depending on the need, the other supported options are (will need to be procured by you directly from open market) – Wired SIP phones (may require additional networking equipment like Switches), Wireless SIP Phones, Tabs, Desktops/Laptops/Mac.
    Crux LX is capable of forming a closed loop communication amongst a group of trusted Crux LX devices over internet. This is done via Inter Asterisk Exchange setup that is supported by Crux LX. When deployed in this configuration, your New York office can call London office as though making a call within office though it will be routed over internet. This can be made secure by use of VPN software. Individual users can also connect to the Crux LX device in their office, even when not in office but connected to internet. In such a scenario, the user can make and receive calls even from outside, as though they were still present in office.
    Yes, a live demo of Crux LX is currently available. A US DID over a SIP trunk and a Singapore GSM trunk line have been configured on the demo unit. One may experience it by dialing +1 408 498 9040 for SIP or +65 8303 4332 for GSM.. Both calls will land on Crux LX and will be greeted by the same message over an IVR that will guide you to punch 1 to speak with Crux Labs’ founder, Rohit, or dial 2 to leave Crux Labs’ team a voicemail message or feedback. This demo will give you an idea of things you can do with Crux LX, all by itself. In the demo, you’ll note that Time Groups and Schedules are being used (9am to 11pm SGT – you hear options, 11pm – 9am SGT you hear office closed), IVR (voice recorded on Crux LX through the Systems Recording interface and setup over IVR), SIP and GSM trunks, Ring Groups (when you dial 1, 5 extensions across the world will ring in parallel), Call Recordings and Voicemail (as soon as you leave a voicemail, an email is triggered to Crux Labs team that a voicemail has been left and Call Data Records (a complete auditable log of calls from origination to termination). Setting up this demo on a boxed unit took us about 1 hour, which included recording messages etc.
    Crux LX works well with Linphone and Zoiper. We recommend Linphone given its tidy interface and capability to integrate chat and video calling through the same interface. It also has easy to use call forwarding and call conferencing feature on the dialpad screen that comes in very handy. It also allows multiple profiles to exist, which is quite useful when you wish to have one profile while in office and another that allows you to connect over internet, when you are not in office network.
    Crux LX in current form is fully built using open source hardware and software. The hardware uses a Raspberry Pi® board and the software includes Debian® operating system and a large set of software that accompanies the Debian® 2.8 distribution. Some of the key FOSS components that support the unified communication and management functionality are Asterisk®, FreePBX®, Chan_Dongle, and RaspAP Web GUI. These are being used under the realms of GPL, AGPL and LGPL licences. At Crux Labs, we have glued it all together along with our own set of modifications that have made Crux LX an easy to use and manageable device. Crux LX is Crux Labs’ attempt to make open source work for non-techies in a way that is simplified, easy to manager and cost effective as compared to other commercial products available in the market. This endeavour could not be possible without the large community of open source contributors world-wide that has offered us this opportunity to make open-source consumable for the society.

    Trademarks and Copyrights – Raspberry Pi®, Debian®, Asterisk®, FreePX® are respective registered trademarks of Raspberry Pi Foundation, Public Interest, Inc., Digium, Inc., and Sangoma Technologies.
    Crux LX works off a 16GB microSD card. About 4GB of space is used by Crux LX software image. About 10-12GB of space is free and available to Crux LX for making backups, call data records and call recordings, that can be backed up to a laptop/desktop from time to time.
    Crux LX has 4 x USB 2.0 ports – , 1 x Composite/Audio port (disabled), 1 x HDMI port (disabled) and 1 x Micro USB port – for Power.
    Yes, any USB dongle with audio and video content on it, when connected to USB ports on your Crux LX, will appear as a DLNA source on DLNA-enabled players or directory services on android, windows and iOS/Mac platforms. The folder appears as “Crux LX Media Server” with sub folders “Browse Folders”, “Music”, “Video” and “Pictures”.
    Our orders will ship from Singapore centre using Air service from one of the top-tier logistics providers – UPS, DHL or FedEx, depending on destination and shipment size. Tracking information will be provided where available.
    Shipping in Singapore is free of charge at this time. Shipping to all other locations is kept at S$30 for simplicity. In most cases, it will be likely more than S$30 which Crux Labs will absorb. For bulk buys of 12 units, the shipping in Singapore will be S$50 and $200 for the rest of the world.
    In Singapore, Crux LX will not attract any customs duties or GST, at this time. To all other locations, Crux LX shipment will be subject to local customs duties and taxes that will need to be absorbed by backers themselves. Note that we cannot alter the value of your rewards in customs declarations. Hence, the value will be declared as the total value of the items contained in the shipment.
    Crux LX comes with 1 year warranty on the hardware across all rewards categories. However, there are no warranties on the software as we largely use open-source. However, the open source we use is quite ppular, hence, has active communities and many a times proactive fixes. Our warranty includes Crux LX Base Unit, Power Adaptor, micro SD card, and GSM Dongles purchased from Crux Labs, subject to normal and indicated product use. The micro SD card shipped with Crux LX is non-transferrable and non-interchangeable. It should never be removed from its slot. Any deviations or tampering against this policy will void warranty. We will try our best to settle warranty in-country in Singapore, India and US, but in other parts of the world, you may have to ship it to the closest of these three countries, at your own expense. For Singapore, India and US, the local backers may still need to ship it locally to the contact points. The shipment for the replacement unit under warranty will be borne by Crux Labs. We are working with global distributors to find a way to ease this as quickly as we can. Once we have some backers supporting us, we may be heard better.
    Unfortunately, we don’t offer refunds or returns at this time. Contact us at to help you make an informed decision.