You haven't put enough information here about your context to get a useful answer. I would suggest you take a look at your project and testing goals, and create your own high level test plan. You should get review on content and approach from the people you work with.
High Level Test Plan/ Test Scenarios for Telecom Based Applications- OSS and BSS
New to Telecom Domain- Need sample Test Plan or Test Scenarios or some document to kick start Telecom Based applications.
IF this is not specific, I would like to receive whatever documents available to begin telecom based testing.