This is not primarily a dependency configuration issue. The Omnichannel Telephony Power Virtual Agent Extension is failing because its prerequisite, Power Virtual Agents Telephony Extension (mspva_TelephonyExtension), was not installed successfully.
The first error “CAB file required for importing solution” indicates that the required Microsoft-managed solution package is not available for import in your environment. Therefore, manually retrying the second extension will continue to produce the missing-dependency error.
For a 30-day Customer Service trial, I would not recommend manually installing these internal extensions from the Dynamics 365 Apps list. The current trial is provisioned with the supported Customer Service/Contact Center capabilities, while some voice functionality has specific trial limitations. Microsoft currently documents that the enhanced voice experience isn't available in the Customer Service trial.
If your objective is to test voice + Copilot Studio, use the supported Voice Channel trial/provisioning process rather than manually importing the telephony extension solutions. Microsoft documents the Voice Channel trial separately through the Microsoft 365 admin center and requires the appropriate trial subscription and provisioning.
In short: don't try to resolve the second error independently. The root cause is the failed mspva_TelephonyExtension installation. If the required package isn't provisioned for your trial, this cannot be fixed by adding the dependency manually; you need to use the supported trial provisioning path or a properly licensed environment
