An off-the-shelf option to communicating after a disaster are satellite phones.  The is problem is most like cellphones.  Satellite phones at present cost around $6,000; more than the value of the cars many people own.  Usage time costs about $10 per minute.  Satellite phones are clearly not an option for almost all individuals.  However there are affluent neighborhood associations which have/are buying satellite phones with their pooled resources.  Even with a satellite phone the basic problem of communicating between citizens is not solved.  If the families that could afford to outfit each member with satellite phones, it is unlikely that each family member will carry these bulky and heavy phones in addition to the cell phone they are probably already carrying. 

Even if one had a satellite phone, it still connects to the telephone system.  That system may either be down or clogged.  If it is working, those you want to call may not have a working phone.  Also keep in mind this is a technology which is behind cell phones in terms of having more dropped calls and bad signal quality.