In my own life, I'm a big fan of technology. I love the internet, my smart phone is always with me and being able to email rather than snail mail is wonderful. But there's one area where it really sucks.
Think about all those novels pre-mobile phone era. Being unable to contact someone was a legitimate conflict or plot device which could ramp up tension. How about a letter lost in the mail? Yeah, could have happened.
Nowadays it just doesn't work. Sure if your hero and heroine are having a fight, the heroine might not answer the phone the first couple of times the hero rings, but it can only go so far before she just seems sulky. And of course her hero could visit, text or send an email. Would she really delete it, or would she be curious enough to read it? I know I'd read the email!
For something like that to work, you really need to make sure the justification for the non-communication is strong and clear. A flat battery excuse will only hold for a short period of time.
And if your only conflict is something that could be resolved with a phone call, that's generally a sign your conflict isn't strong enough, especially for a black moment. Which for me means it's back to the brainstorming board to come up with a damn good excuse for my hero to ignore my heroine's communication attempts. Sigh.