Here are some specific prompt guide and examples for common situations you might encounter in building a voice agent.
Many of these patterns — including phone number pronunciation, email spelling, and speech normalization — are now available as one-click presets in the
Agent Handbook.
Pronounce the phone numbers
We’ll utilize the Read Slowly feature to add pauses between words. For more information, see the Speech Controllability documentation.
It’s recommended to include a prompt as a guideline for the LLM to follow. This ensures that the agent can consistently reply with the correct format, even if customers double-check the phone number.
When people ask about your phone number, your phone number is 4158923245
## Guideline
When speaking the phone number, transform the format as follows:
- Input formats like 4158923245, (415) 892-3245, or 415-892-3245
- Should be pronounced as: "four one five - eight nine two - three two four five"
- Important: Don't omit the space around the dash when speaking
Pronounce the email
## How to spell out
The possible email format is name@company.com
to spell out a email address is n-a-m-e-@-c-o-m-p-a-n-y-dot-com,
@ is pronounced by "at".
Pronounce the website
Whenever you encounter a website URL, please:
Identify each segment of the domain name.
If a segment consists of individual letters (e.g., "NK"), pronounce each letter using its spoken form in English (e.g., "N" → "en," "K" → "kay").
If a segment is a recognizable word (e.g., "laundry"), pronounce it normally as that word.
Pronounce "dot" before stating the top-level domain (e.g., "dot com," "dot net," "dot org," etc.).
Example:
"nklaundry.com" → "en-kay-laundry dot com"
"abctest.net" → "A B C test dot net"
"xyzco.org" → "ex-why-zee-co dot org"
Adhere to this phonetic breakdown carefully to ensure clarity and proper pronunciation for customers.
Pronounce the time
For State Numbers, Times & Dates
For 1:00 PM, say "One PM."
For 3:30 PM, say "Three thirty PM."
For 8:45 AM, say "Eight forty-five AM."
Never say O'clock, Instead just say O-Clock.
Always say "AM" or "PM".
Handle being put on hold / no response needed
For non-reasoning models
We hard-coded a stop sequence in the LLM: NO_RESPONSE_NEEDED. Whenever this sequence is met, the response generation stops.
You can then prompt the LLM to output nothing by writing something like:
- when user says hold on, reply exactly the following: "NO_RESPONSE_NEEDED".
For reasoning models
Reasoning models like gpt 5, gpt-5.1 does not support this feature. You need to prompt engineer it differently to achieve this.
When user says hold on, simply do not respond. 
