You are correct if you are filing married filing jointly and "covered" by an employer's retirement plan.
You can always contribute to a traditional IRA, regardless of your income or coverage by an employer plan.
The deductibility depends on your income, filing status, and employer coverage.
These links provide the most recent income limits for deducting IRAs
IRA deductibility - covered by employer plan (the "retirement plan" box on your W2 is checked)
