The emergence of dual SIM phonescouldn't have come at a better time enabling you manage multiple numbers in anage characterized by communication overload, as a matter of fact some peopledon't like receiving calls preferring text which is perceived as safer. Thesedual SIM phones allow you separate your callers, the call blocking feature onthe  dualSIM phone is especially useful to block calls from unwanted and pesky callers pestering you with "Private" or "Unknown" calls, SIM2 has the ability to reject and block those "Private" or"Unknown" calls.

Let us not forget to mention theconvenience and option the dual SIM phone provides allowing you freely toggle between cellphone networks and using the best voice plan anytime, never mind dodging the shackles ofroaming charges when you travel abroad, simply by purchasing a local SIM cardand inserting in second SIM for cheap communication in foreign territory whileleaving your "home" SIM card in one SIM so there is no break incommunication from home and people that need to reach you while youoverseas. 

Another great advantage is theability to use the dual SIM phone for your virtual office applications, runningyour office and private calls on two separate SIMs.

People now see the needto distinguish their work and business number from a social number. Having thebusiness number for work, office and business related calls. And the socialnumber for acquaintances, social network contacts and others?

Personally I use a dualSIM phone and I find it hard to believe how the singletons (nickname for singleSIM cell phone users) manage things with single SIM cell phones. 

If you must use a singleSIM phone, it better be a smart phone like the palm, Blackberry's etc becauseas far as I know those provide complete enterprise solutions, other than thatyou will not be excused in these times for using a bland single SIM phone.

By the way, don't thinkof asking the global cell phone networks for a dual SIM phone, it goes againstwhat they stand for... "Lock-in", "Contracts","Plans" and what not. Dual SIM phones do not give them that control.They will only list and supply dual SIM cell phones with the assurance you won?tuse a competitive SIM card in second SIM? Of course, that defeats the entire purpose