Question : Cannot transfer calls between Asterisk and Legacy Avaya Definity G3R interconnected with a T1 card.

I have interconnected my Asterisk server with a legacy Avaya Definity G3R. I have different dial plans on the  2 systems (3 digit on Avaya and 4 digits on the Asterisk). However, I cannot transfer calls from the Avaya system to phones on the Asterisk system. Calls transferred give a busy tone.

Answer : Cannot transfer calls between Asterisk and Legacy Avaya Definity G3R interconnected with a T1 card.

I have looked through the documentation and it all looks reasonable. One part does concern me however.
In the inbound asterisk setup it mentions replacing a file in asterisk 1.0.10. That version of asterisk is now very old and basically obsolete so you cannot simply replace the file in the current asterisk version as it will have changed too much.
Perhaps the current asterisk has the feature that the patch requires. If it doesnt then you will have problems.

You might want to try joining the asterisk mailing list and asking people there if they have any experience and mention that voip-info page.