Iridium IMF 1000- Calls being dropped at random times
Summary:

This artical describes the problem when calls drop out when using a Iridium IMF 1000
Article:

Symptoms Too many dropped calls at random times Causes · Obstructions between the Iridium antenna and the sky Troubleshooting and Resolution · Ensure that the Iridium antenna has a clear view of the horizon in all directions. Move the antenna if necessary.