Media for Adsl+sip+did

We are a small solution company in I ndia , we want to make a VOIP

solution package for SMEs who would like to have a Virtual Phone Number

in U.S and other countries . For this we want to use the existing

internet infrastructure mostly avaliable to businesses which is ADSL

256Kpbs to 512kpbs . We want to use DID (virtual phone number providers

) providers which support SIP like

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etc and have the calls

from the phone numbers in U.S or other country to be fowarded to SIP

numbers which will be answered in Indi a at offices of respective

offices who owns the DID number .

We need advice to achive the following which is based on cheap solution

or product like Cisco ATA & VPC1000 FXS to FXO Port Converter by

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, Most SME business owners wants the calls

recieved from U.S which can be of potential customers should be

answered by them than an employee of the company so we need a solution

which can make calls receieved on standard phone device using similar

to ATA in the office or fowared to mobile phone of the owner using a

PSTN line of their office after recieveing the call from SIP using ADSL

in the same office .

Diagram:- U.S Local No(DID )- SIP(pulver.com)- Internet- India(ADSL)- SIP Phone

/ Fowarded to Mobile Using PSTN line.

Can some one suggest such a solution , It would be breatly appreciated