IP Office Technical Tip (Region: Global)

199: Data Channels Not Being Released Cause Voicemail Issues

23rd January 2008 - Full PDF Text Version


An issue with data channels not releasing correctly has been found when using IP Office software releases 4.0.10, 4.0.14 and 4.1.9. Voice callers will experience ring tone no reply or busy tone with voicemail ports available.

The issue can be recreated in a number of call scenarios:

  1. A call is placed to a hunt group (it doesn’t matter if the call is directly to the hunt group or has been transferred to the hunt group), and a user within that hunt group is idle (has no other active or ringing calls). If the voice mail timeout expires while there are other ringing calls on that extension (either calls directly to that user, calls to the same hunt group or calls to a different hunt group that contains that user), the call will never be placed to the voicemail, but the voice mail channel will remain allocated.

  2. A call answered by Auto Attendant is routed to a user within a hunt group and another call type (DID or Internal) simultaneously rings the same user within the hunt group. If the DID or Internal call is answered first the data channel presenting the hunt group call may not be released, causing a port to lock up. (Please see SSA below).


Note: Call Waiting must be set to "ON" on the Collective hunt group and on the user within the hunt group.

When this happens you will receive a busy tone when trying to access voicemail internally and ring tone no reply when reaching the Auto attendant.

When viewing SSA you will see more data channels in use than voice mail channels - this is an indication of data channels locking up (See Note A below for when Data Channels are used by the system). You will also see large congestion counts as voicemail is not answering even though it shows channels available.


If you experience this issue you have three options available to you.

  1. Remove call waiting from the user or the hunt group.

  2. Change the hunt group to a different type (other than collective).

  3. Contact your distributor or open a ticket via iCare and reference Avaya CQ 39339. This will generate a ticket to Avaya Tier III who will supply Critical Patch number 4.1.9 5501 to fix the issue. (The customer will also need to upgrade their Voicemail Pro to version 4.1.26).

The above screen shows that the IP Office has eight voicemail channels licensed and at this time there are three connections to voicemail active, the data channel usage count shows six active channels, therefore this would indicate there are 3 data channels in a locked state. On this system only five users would be able to access voicemail concurrently, the three other callers would receive either ring tone no reply or busy.


Note A: Data Channels - from Knowledgebase on 4.1
Data Channels are used for Remote Access (RAS), Internet Access, and Voicemail sessions. A data channel is an internal signaling resource used whenever a call is made from the IP network to an exchange line (Central Office). For example, four people surfing the Internet will use a single data channel since they all share the same line to the ISP. Two people remotely accessing the Office LAN from home will use two data channels since they have dialed in on separate lines. IP telephones do not use data channels.