Get proxy-server settings connected with IP-address received by DH

The situation is as follows:
A notebook user goes from one city to another. He connects to the local
network, where his netcard MAC-address is recognized and receives IP-address
through DHCP. BUT - the settings of the proxy-server differ from those in his
native city - the result is - he has no Internet connection. He needs to
change proxy-server settings manually each time he comes to this city.
Is there any way to make it work automatically? So that the notebook
received IP-address and the proxy-server settings changed automatically.
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Best regards,
Oiprox