Since almost a year ago I work from home and travel to visit customers, this makes me be close to the customers, but for the some of the delivery teams I have lost the capacity to have face to face interaction, that now is limited to a couple of times a year.
I found this interesting analysis of the Dumbar’s number in this article. This basically confirms what I already know and feel (you need to invest more time in communications, be patient and focus more on the relationships), it just create the concept of Dumbar’s number that tries to standardize the behavior.
Looking more about the concept, I found this interesting picture done by Joe Glynn, that really contributes to visualize some more real examples with some of the communications channels almost all people use.
WordPress
Google + 
Facebook