What is the cross boundary call frequency?

All around the country you will be within the reach of "Athens Information" (if you fly VFR), on frequency 130.925 Mhz (North Sector) / 119.75 (South Sector). This station will provide you with (non radar) Flight Information Service and will give you all information about activated military and restricted airspaces. While flying VFR at low altitude, you may lose contact with FIS station. In that case, continue to fly according to your flight plan, on VFR, and wait for a contact later on. A contact must be made at least every 30 minutes. It is however advisable to contact the Approach or Tower frequency of any military unit whose airspace you will be transiting.

Military airports usually have associated TMA's and you should contact the published frequency. You can also contact TUGRIT military radar on 129.80 for advisories.There is a new (from spring 2010) FIS service specifically for Athens TMA area while above FIS frequencies remain in effect for the rest of Greece. Athens Approach now offers FIS service dedicated to Athens TMA area on frequency 124,025. Refer to LGGG FIR NOTAM A0319/10 for details.