Author Topic: T.38 faxing on MCD with TDM and with SIP trunks: questions  (Read 1626 times)

Offline Curtis-at-Travis

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T.38 faxing on MCD with TDM and with SIP trunks: questions
« on: August 28, 2020, 09:34:54 PM »
I have a customer who is wanting to replace a fax server that is currently connected to an MCD using PRI channels.  The new server will use SIP.  The provider of this server has got my customer convinced that he needs to use T 38 for the connection to the MCD. 
Currently, the customer has outside trunks that are connected with PRI. So to my way of thinking, T 38 isn’t going to even work for these connections to the outside world. I don’t believe that the provider is going to be using T 38 over these lines.

Plus there is the added factor that they will need to purchase a DSP II Card and T.38 licensing.  Additionally, The incoming trunks are located on one MCD and the current fax server is connected to a second MCD.  The calls are routed using IP networking. 
According to tech-support ( who I am beginning to doubt),  I would need T 38 licensing and DSP2 cards on both MCD ‘s. Now the price is jumping to over $7000 for a feature that may or may not work.

Additionally, the customer is talking about switching over to sip trunking. I know that SIP provisioning Does Support T 38. But the way I understand things, the audio transport would actually be between the MBG and the Fax Server (point to point), and the MCD doesn’t actually get involved at all with audio.  So, if that is the case, do we actually need to invest any kind of money in T 38 licensing and hardware?  In all actuality, if this phone system was a virtual server, I wouldn’t have any DSP hardware involved in this after all.

If anybody can help me clarify any misconceptions, I would greatly appreciate it. I’m all for selling stuff and making money, but I also like to do it ethically.


Offline acejavelin

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Re: T.38 faxing on MCD with TDM and with SIP trunks: questions
« Reply #1 on: August 29, 2020, 05:33:59 PM »
Sadly, you do need a DSP II and associated licenses for T.38 for this scenario since the fax server is on element B and the trunks on element A... Unless you want to move the fax server to element A.

Offline Curtis-at-Travis

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Re: T.38 faxing on MCD with TDM and with SIP trunks: questions
« Reply #2 on: August 31, 2020, 11:32:36 AM »
What if the trunks don't support or use T.38?  What is the point?

Also, if we started using SIP trunks, TDM is not even part of this scenario is it?  Why would we need DSP II resources or T.38 licensing if the communication is point to point between the server and the BGM?


Offline johnp

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Re: T.38 faxing on MCD with TDM and with SIP trunks: questions
« Reply #3 on: August 31, 2020, 05:19:18 PM »
The t.38 licenses and DSP-II come into play when coming fro another site via ip trunking and faxing out from TDM. IP and fax sucks IMHO. I think it worked across ip trunks until Mitel started selling T.38


 

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