Creating extension for PSTN number with extension

I'd like to set-up an extension to dial my work. To do so, however, the system would have to call a PSTN and at the phone tree, then dial my extension. Is there a way to build-in an option to dial a PSTN, pause for a set number of seconds, then dial a 4-digit extension? (For example, program PSTN extension for 212-555-1212PPPP1234.) Thanks for your help!