Phone Systems-Voip vs Digital PBX

Hi,

e are looking at replacing our phone system. We have Nitsuko phone switch using an analog T1 (no PRI) and we are running out of ports on the line cards. This phone system is 18 years old.

We have been evaluating a VoIP system and a hybrid digital PBX system as replacements.Two proposals have us looking at a ShoreTel system, and one looking at a system made by a company called Vertical.
I had some questions:
1) Are Digital PBX's or this hybrid type unit obsolete? Is the industry moving to IP phone systems?
2) For home offices, will there be any charges for making local calls if they are tied into an IP system at a home office?
3) How complicated are these systems?
4) How much bandwidth do VoIP systems take up?
5) Do the handsets on these units break real easy?

Please help.

I didn't find the right solution from the Internet.

References:-
https://arstechnica....topic.php?t=1155139
<a href="https://wer.fgy.com">text</a>


Thanks!