Role dependent, but generally no problem with it. Every 6 weeks or so everyone technical gets together in the office anyway to catch up and talk about planned stuff, so it’s not like we never see each other. Most of us do work for customers on site but when we don’t need to be there’s no compulsion to be in the office if you’re just writing up docs or similar. Some people live far enough away that they’d not come in, some close enough that most days not on site they spend in the office.
We use Lync (given that’s what the company does!) so anywhere we’re online we can get our calls, easily see who’s online, screen share, etc. No reliance on a desk phone – hardly any of us have them. Any reasonably forward-looking company is providing ways to let their employees work effectively from outside the regular office.
Tricky discussing it with a prospective employer, but if you definitely don’t want to work for a company with a big commute that needs you there 5 days a week then no harm in discussing at interview. May be worth asking more generally about home working (inc how many existing people do) before talking about what you’re looking for.