1) attend the manufacturers authorised training course.
2) ensure you are familiar with Data networking
3) Attend the manufactures authorised training course
4) study all published documentation & guides (Avaya has very good IPO Docs)
5) attend the manufacturers authorised training course.
I know 1, 3 & 5 are the same but it is so important I felt it worth repeating.
A Maintenance contract is essential, not a Luxury.
Do things on the cheap & it will cost you dear