[asterisk-biz] need creative solutions for number portability

I'm presently working on an office move and evaluation of telecommunications services needed at the new location.  I'm presently wrastling with an issue related to portability and geography between landline carriers.  Presently certain people within the organization are hopelessly in love with our 909-822-xxxx number(provided by pacbell/att).  As that number is presently provisioned it rings to a location geographically within 909-822 and forwards all calls to another number 909-944-xxxx (Verizon)  Because of this toll is paid on all incomming calls. )  The office is moving to another verizon area (909-899, actually north fontana) and is just feet from the ATT/Verizon border.  Verizon tells me the 909-822-xxxx number being held by ATT can not be moved to ring direct into the new location, so toll charges for inbound must still be paid.  I was hoping to avoid that.

What are the issues involved here?  Technically with SS7 it would seem a number could ring anywhere.  my 909 npa cell phone works just fine when on vacation in 941 or 808 and my 206 VoIP line finds me anywhere I have a connection to the net.  What prevents this from being true with landlines?  If this is a geograpic vs non-geographic issue then where can I find street level maps of what wire center serves what area thereby finding where to locate to be within a specific npa-nxx?  Other than porting the number to VoIP, what solutions are available so inbound calls incur no toll charges to the called party?

Eric