Posted on

Implement QoS for 3CX VoIP on Debian Linux

If you need QoS on your Debian Linux system, this step-by-step guide shows how to create a rule for iptables that tags all traffic from the machine with a higher QoS so as to ensure traffic is given priority.

Step 1: Making sure your QoS rules are applied permanently to your system

By default, your Debian Linux system will NOT save any rules applied at runtime. This can however be resolved by adding the iptables-persistent package to your installation as follows:

apt-get install iptables-persistent

This will create a new file in “/etc/iptabes/rules.v4” that will be loaded at each system and service restart. 

Step 2: Create a Rule to Tag All Traffic Originating From This Machine

Run the following commands at the command prompt:

iptables -t mangle -A OUTPUT -p udp -j DSCP –set-dscp 56

iptables -t mangle -A OUTPUT -p tcp -j DSCP –set-dscp 56

Step 3: Checking QoS is Applied to Outbound Traffic

Use tcpdump to create a network capture file for you to examine using Wireshark on some other computer:

tcpdump -s 0 -w 247-check-dscp.pcap

Download this file onto your PC, and open it with Wireshark. You can check that outbound traffic is indeed being tagged with the correct DSCP value:


Step 4: Make Sure the Changes are Saved Permanently

Run the following commands at the command prompt:

iptables-save >/etc/iptables/rules.v4

Posted on

Custom VoIP – Just the Way You Need It


Recent reports suggest that VoIP solutions are on track to become the dominant form of voice communication, steadily replacing traditional wired phone systems. International market researcher, Infonetics Research, famously forecasted that residential and business VoIP services combined will grow to a valuated $74.5 billion by 2015.

This valuation is reinforced by a highly competitive market contending to offer better quality services that costs less, enticing more customers into investing. Apart from that, VoIP technologies are extremely customisable, allowing businesses to dynamically adjust the technology to meet their user requirements.

Custom VoIP – Challenges Faced Configuring VoIP Technology

Expanding on the need for customisation, users often have different needs based on their role and responsibilities. As an example, if users in an organisation do not require conferencing, the button associated to that function can be repurposed to a feature they actually need, like speed dial or an additional line.

VoIP technologies including VoIP providers, PSTN gateways and IP phones can be configured manually or receive their settings from xml templates. When dealing with many devices such as IP phones,  manually configuring and customising each device individually is a cumbersome task.

The process is prone to human error and lacks lower level customisation options not typically available through configuration consoles.

Custom VoIP – Break Free from Restrictions

247SupportedLogoCreating and using customised templates is a quick and efficient way to assign a common button configuration to large amounts of phones, at one go.

Although VoIP solution vendors provide facilities to customise templates, these customisations are not supported by the vendor and left up to the customer to figure out and deal with issues as they arise. Thats where 247 Supported fits in.

247 Supported’s vast expertise in VoIP solutions boasts specified knowledge in template customisation. Templates are customised, tested and further supported as you, the customer needs them, when you need them.

Stay ahead of the challenges faced when customising templates and always have a helping hand to turn to when things go wrong with 247 Supported today!



custom voip –

custom voip –

custom voip –

Posted on

500 Registering Glare Condition

Sometimes, when a SIP Clisnt registers with a VoIP Service, the VoIP Service rejects the request with the following SIP Response:

500 Registering Glare Condition

 What Does it Mean?

The SIP Client is attempting to register with the service, but the service already has an active registration for the SIP Client. This can happen when the SIP Client needs to RE-register (because of some change in settings, for example), but does not UN-register its previous registration beforehand.

How Do I Recover From a Failed Registration Scenario?

To re-activate the registration for your SIP Client:

  • deactivate the account on your SIP Client
  • wait for the service to expire the previous registration (the time to wait will be equal or greater that the SIP Client’s configured Registration Interval)
  • reactivate the account on your SIP Client

How Do I Work Around the Issue?

To minimise the potential impact of this:

  • Reduce the Registration Interval of your SIP Client to a smaller value (120 seconds is a reasonable minimum value)
  • When you need to make changes to your settings:
    • first deactivate the account on your SIP Client
    • adjust settings as needed
    • reactivate the account on your SIP Client when all settings changes are completed