Urgent Help with Mikrotik Router using GPRS PCMCIA Card

Hello There! I want to use and also very needy to use GPRS PCMCIA card with Mikrotik router. I have only one option to access the internet i.e GPRS only here at my end. I have GPRS service activated with a mobile phone company and now want to use this service to access internet through Mikrotik router. I have gone through Mkrotik’s site and come to know that a GPRS PCMCIA card along with SIM card can be connected to get internet. Please let me know from where i can get this GPRS PCMCIA card, as i want to buy it. Secondly please let me know can i access other Mikrotik routers at remote site, which are running on different ISPs by establishing a PPTP link while using GPRS PCMCIA card?

I shall be very grateful to assist me on it and will appreciate any help in advance.

Thanking you and looking forward to the pleasure of hearing from anybody out there to assist me on this issue as soon as possible.

Sincerely,
Permender
Mikrotik Router boards Trainee