No. Can you borrow an analog phone? You can probably buy a used phone from Goodwill for a couple dollars.
When you add your OBi202 to OBiTalk the configuration will probably get reset. Before you start, take a configuration backup using the OBi Version. Backup is found under System Management/Device Update. After you add the OBi202, do a configuration import into OBi Expert using the backup. Backups do not contain password, so you will have to manually update them. You will probably have to delete the GV trunk and then re-define it.