So if I were to move my Exetel ADSL2 from AAPT infrastructure on the BYO plans to Optus infrastructure under the INCTEL plans, I could then make the PSTN to VOIP transfer without losing my PSTN line? (that is, I presume another PSTN number would be allocated to me by Optus to replace the number moved to VOIP?).
You would still lose your line in terms of making phone calls via PSTN. The difference would be that you would keep your ADSL2 service with Exetel because we would essentially do all the magic behind the scenes to ensure you have a VOIP number that is ported from your PSTN with exetel while retaining your ADSL2 service with us.
I am considering changing from a old plan with included Optus line to a naked plan transferring my existing phone number to VOIP. I have one concern, that is if I decide to change from exetel in the future am I able to retain my Phone Number if I port away.
Once your number is ported to VOIP through Exetel, you can indeed then port the number to another provider(be it VOIP or PSTN). We have the account number needed should you decide thats the case.
The following line in the agreement concerns me;
"I understand that my telephone number will be deleted and cancelled and become non-usable and non-transferable to another carrier thereafter."
That is a condition for standard Naked ADSL2 activations without the 'PSTN TO VOIP' option. Provided you correctly filled out the PSTN to VOIP section and selected 'YES' and of course, that is passes qualification that should be fine. I'll have this changed to correctly reflect the circumstances of that check box - thank you for pointing this out.