Aatrox Communications enjoyed working with a partner recently on a rather sizable 3CX deployment.

Jabra 930

  • 64 concurrent calls

  • 3CX instance hosted onsite

  • 3CX softphones with wireless headsets (Jabra 930)

The majority of calls made by the customers business were outbound mobile calls, costing them tens of thousands of dollars per month – ouch!


Aatrox Communications, together with our partner, proposed the idea of utilising both Unlimited SIP Trunks and PAYG SIP Trunks.

Using two separate trunks allows us to implement some pretty smart routing using outbound rules. This routing sends all mobile calls over the unlimited trunks and all local and national calls over the PAYG trunks.

The customer (unsurprisingly!) loved the idea of saving money on their phone bills. We carried out some modelling using their last few phone bills, and they went ahead with 24 Unlimited SIP Trunks and 40 PAYG SIP Trunks.


A bit about the Aatrox Communications side –

We run two different SIP Trunk platforms for Unlimited SIP Trunks and PAYG SIP Trunks.

When mixing an matching, we need to decide which trunk inbound calls come in on (and as they don’t cost anything, Unlimited vs PAYG doesn’t matter). As this customer chose to have 40 PAYG trunks and 24 Unlimited trunks, it made sense to use the larger trunk. Behind the scenes, a different pilot number gets assigned to the Unlimited SIP Trunk for authentication from the 3CX phone system, but we stamp the caller ID from one of the numbers hosted in the PAYG SIP Trunk over the outbound call of the unlimited SIP Trunk.

This means that regardless of whether users get routed over the PAYG trunks, or over the unlimited trunks – the person receiving the call is none the wiser, and just sees the usual caller ID.


In order to make this work, the Outbound rules were set as followed:

  • Unlimited SIP trunks was set to route 1
  • PAYG SIP trunks was set to route 2
  • Any numbers with the prefix 04 or +614 were set to route 1


When configuring the Unlimited SIP Trunks, we set that the maximum number of simultaneous calls on that trunk is 24. This means that no more than 24 calls can run through the trunk at any time.

Should this maximum be reached however, instead of dropping the call, it would automatically be routed to the PAYG SIP trunks.

3CX Features


This solution was implemented successfully with some great feedback from the customer to the partner, namely the features of 3CX. In the words of the customer, the 3CX features were “chalk and cheese” when compared to their old phone system.


Even more excitingly they have reduced their phone bill by a whopping 65% – and in their case, that equates to savings over $50,000 per year!

This implementation highlighted the need for an experienced SIP trunk provider, looking to find real solutions for the business.

Find out more about our SIP trunk plans, or get in touch with us to find the best solution for you.