You can use OfficeRoute from
www.2n.czThere are some local suppliers. However, these are LAN-based, can do SIP or H323. Not sure if they meet your requirements, but
1. They support multiple GSM lines (upto 4 lines)
2. Supports Voice and SMS (and one port can be 3G enabled if you go for the UMTS version)
3. You can connect them to your machine - via the LAN.
4. They can communicate with Asterisk via LAN (but that is where your requirements get my head whirling!)
Whoever told you about them should give you the manufacturer and mode numbers - Sangoma, etc... and you can search the websites first before asking here:)