Asterisk-Voicemail: SIP-MWI to ISDN-MWI Translation Issue


Hopefully someone in the “Asterisk Wide World” can help me on this.

I have a new Asterisk-Voicemail platform, running on Asterisk I have a problem with the SIP Message Waiting Indication message from the Asterisk, which is being translated by a Media Gateway into an ISDN-PRI message, in accordance with ETSI 300 745.

To illustrate the flow:

Asterisk-Voicemail <-----> Media Gateway <------> Siemens EWSD

Furthermore, the EWSD is the Class 5 TDM Exchange that can only talk ISDN-PRI on this solution. Then, the EWSD is where the CPE (analog Customer) is connected, that needs the MWI. The Media Gateway is a Cisco MGW, or OneAccess MGW, either.

The voicemail box (e.g. Customer’s voicemail box) is in the Asterisk platform, being the Voicemail server for this solution.

So the call flow is, if an EWSD Customer is call forwarded to his voicemail box, and anyone (e.g. any Caller) dials that Customer, the EWSD sends that call to the Asterisk-Voicemail platform. The caller leaves a message, and the Asterisk will send MWI back to the EWSD.

The issue that we’ve seen is:

The EWSD receives ISDN: MWI_Indicate message via Facility Information Element from the Media Gateway. Unfortunately, the MWI is not triggered to the end-Customer on this message. Basically, the EWSD needs ISDN:MWI_Activate as per ETSI 300 745.

Troubleshooting further, we’ve noticed that the Asterisk was sending SIP:NOTIFY (MWI) to deliver the MWI message back to the MGW which will ultimately reaches the EWSD. Based on the research we’ve done so far, the Asterisk (thinks) that it is the “network” which is providing the MWI to an endpoint. The ETSI 300 745 states that the ISDN: MWI_Indicate is for a “network” to advise the “user” of the MWI message. In the solution illustrated above, the Asterisk is NOT the Network, rather, it is the “Controlling User” as defined in ETSI 300 745 (Annex A in particular). In the solution, the EWSD is the Network. However, the EWSD requires to receive ISDN:MWI_Activate, a “Controlling User” to “Network” advice, this is in accordance to ETS 300 745.

The question i have is, is there a way somewhere in the Asterisk that will enable to send a SIP:MWI_Activate, rather than a SIP:MWI_Indicate message to the MGW.

In the initial investigation, i thought the problem is the MGW that i’m using, which is unable to send the proper ISDN:MWI_Activate to the EWSD. But it seems that the problem is the source of the MWI message, or the COntrolling User, which is for this case, the Asterisk platform.

Thank you in advance.