Liberty Converse not routing outbound traffic on busy

When NHS Grampian moved to Netcall Liberty Converse we also took the opportunity to migrate from DPNSS to SIP trunking between out Mitel 3300 controllers and the Netcall Servers.

The setup is as follows

We have two Mitel 3300 telephone system controllers and two Netcall telephony servers. We have 45 channels of SIP going from each controller to each server giving us a total of 180 channels. These are then split on the Netcall side to a 2:1 ratio (As requested by NHS Grampian). I.e. for each 45 channel sip peer profile (4) the calls are split to 30 inbound and 15 outbound. This gives us a total of 120 inbound and 60 outbound channels. This setup was agreed and minuted during project meetings. In addition we have 4 x 5 channels of SIP delivered from 2 x trunking gateways (2 x 5 channels to each Netcall server). This provides NHS Grampian with resilience should there be an issue with a single item of equipment.

What we expect to happen if 30 Inbound channels from one of our Mitel controllers are in use is to receive Busy from the Netcall Server which would prompt the Mitel controller to use its second choice route to the second Netcall Server using its second Peer Profile.

We have starting to experience “503 service unavailable” messages and reported the problem to Netcall. We have been advised that the above setup will not work. Netcall are set up to accept 68 Inbound calls before presenting Busy and cannot split the 45 SIP channels into 30 Inbound and 15 Outbound. This causes issues as we only have 45 SIP channels per Peer Profile so they continue to attempt to route calls back over the Peer Profile as they are happy to receive 68 calls.

Netcall will only use their second choice route in the event of a failure of our first SIP Peer Profile to our Mitel controller and not on Busy as they informed us during the Pre-Installation Meetings,

My questions are:

Is any other site experiencing this issue?

Will Netcall consider programming their servers so that they can route inbound and outbound calls as agreed in the project meetings? The Netcall servers don’t have the capability at present to define inbound and outbound calls for different SIP peer profiles. They can only accept inbound and outbound totals for that servers.

Good Afternoon Derek,

Would you please be so kind as to log this with the support helpdesk.
Send you enquiry to or alternatively call support on 0330 363 0300.

Many Thanks
Adam Mills

I have a ticket open and It was a Netcall engineer who suggested posting something on the Forum. Incident number [NID22032]

Hi Derek
Sorry you are having issues. I have made enquiries within Netcall and I understand the team is actively involved with you in trying to find a solution to this. Indeed, my understanding is that there is a meeting scheduled with our third line support on Thursday.
The intention of our Engineer was that you could raise a request for a feature in our Ideas portal Ideas ( and then any customer having a similar requirement can vote for the feature to add weight. The way it has been described to me suggests that it would be a good feature to add to the product.
Kind regards, Tony Norman