> ## Documentation Index > Fetch the complete documentation index at: https://docs.nixflex.com/llms.txt > Use this file to discover all available pages before exploring further. # Update phone number > PATCH /v1/phone-numbers/:phoneNumber Update the per-number settings on a number you have already imported: the call business profile, the voice, and the SMS and web agent instructions. Every field is optional - send only what you want to change. Any field left out is untouched. Each channel is independent: * `custom_prompt` shapes **phone calls** (layered on top of the agent prompt). * `sms_prompt` is the **SMS agent** ([SMS agent](/sms/sms-agent)) - it does not affect calls. * `web_prompt` is the **web agent** ([Web agent](/web-assistant/overview)) - it does not affect calls or SMS. * `sms_reply_enabled` turns SMS auto-reply on or off for the number. * `speaking_rate` sets how fast this number talks, overriding the agent's speed. * `dtmf_enabled` lets callers type digits on their keypad instead of saying them. * `record_call` controls whether calls on this number are recorded. ## Request ```bash theme={null} curl -X PATCH https://api.nixflex.com/v1/phone-numbers/+447446466847 \ -H "Authorization: Bearer KEY_ID:KEY_SECRET" \ -H "Content-Type: application/json" \ -d '{ "sms_reply_enabled": true, "sms_prompt": "You are the text assistant for Smile Dental. Open Mon-Fri 9am-5pm. A check-up is 45 pounds. You can book, reschedule and cancel. Keep replies short." }' ``` URL-encode the `+` if your HTTP client doesn't do it automatically: `%2B447446466847`. ## Body parameters | Field | Type | Required | Notes | | ------------------- | --------------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `custom_prompt` | string or null | No | The business profile layered on top of the agent prompt on **phone calls**. Maximum 8000 characters. Send `null` or an empty string to clear it - the number then falls back to the agent prompt alone. Does **not** affect SMS or web chat. | | `voice_id` | string or null | No | The voice this number speaks with on calls, overriding the agent's voice (e.g. `Craig`, `Eleanor`, `Ashley`). Send `null` or empty to fall back to the agent's voice. Must be an exact, valid voice ID. | | `sms_reply_enabled` | boolean | No | Turns the SMS agent (auto-reply) on or off for this number. `false` by default - a number only replies to texts when you turn this on. Accepts `true`/`false`. | | `sms_prompt` | string or null | No | Instructions for the [SMS agent](/sms/sms-agent) on this number. Independent of `custom_prompt`. Maximum 20000 characters. Send `null` or an empty string to clear it. | | `web_prompt` | string or null | No | Instructions for the [Web agent](/web-assistant/overview) on this number. Independent of `custom_prompt` and `sms_prompt`. Maximum 20000 characters. Send `null` or an empty string to clear it. | | `speaking_rate` | number or null | No | How fast this number speaks on calls, overriding the agent's speed. `1.0` is normal, `0.5` is half speed, `1.5` is half again as fast. A value outside that range is clamped to the nearest limit rather than rejected. `null` means **not set** - the number inherits the agent's speed, so a `null` number under a `1.5` agent still speaks at `1.5`. To make one number normal while the agent stays fast, send `1`, not `null`. See [Voices](/concepts/voices). | | `dtmf_enabled` | boolean or null | No | Whether callers on this number can type digits on their phone keypad instead of speaking them. `null` means **not set**, so the number inherits the agent's setting - a `null` number under an agent with keypad input on still accepts keypad entry. Send `false` to switch one number off while the agent stays on. See [Keypad input](/advanced/keypad-input). | | `record_call` | boolean or null | No | Whether calls on this number are recorded. Recording is **on** unless switched off. `null` means **not set**, so the number inherits the agent's setting. Send `false` to stop recording one number while the agent keeps recording. The transcript is unaffected either way, and `recording_url` on the call record becomes `null`. See [Call recording](/advanced/call-recording). | Send at least one field. An empty body is rejected. ## Response `200 OK` returns the updated number: ```json theme={null} { "phone_number": { "phone_number": "+447446466847", "agent_id": "agent_125207e452f8714a", "custom_prompt": "Business: Smile Dental Croydon...", "voice_id": "Craig", "sms_reply_enabled": true, "sms_prompt": "You are the text assistant for Smile Dental...", "web_prompt": null, "speaking_rate": 0.9, "dtmf_enabled": null, "record_call": false } } ``` Takes effect on the very next call or text - no deploy, no re-import. ## Errors | Code | HTTP | Cause | | ------------------------ | ---- | ----------------------------------------------------------------------------------------- | | `missing_field` | 400 | Empty body - no updatable field present (send `null` to clear a field, not an empty body) | | `custom_prompt_too_long` | 400 | `custom_prompt` over 8000 characters | | `sms_prompt_too_long` | 400 | `sms_prompt` over 20000 characters | | `web_prompt_too_long` | 400 | `web_prompt` over 20000 characters | | `number_not_found` | 404 | Number doesn't exist OR belongs to a different account | ## Use case: reseller end-customer onboarding One agent template, many end-customers - each number carries its own call profile, SMS agent, and web agent: ```javascript theme={null} // Customer edits their business details in YOUR app -> you sync to Nixflex await fetch( `https://api.nixflex.com/v1/phone-numbers/${clinicNumber}`, { method: 'PATCH', headers: { 'Authorization': `Bearer ${NIXFLEX_KEY_ID}:${NIXFLEX_KEY_SECRET}`, 'Content-Type': 'application/json' }, body: JSON.stringify({ custom_prompt: `Business: ${clinic.name}. Address: ${clinic.address}. Open ${clinic.hours}. ${clinic.services}`, voice_id: clinic.voice_id, sms_reply_enabled: true, sms_prompt: `You are the text assistant for ${clinic.name}. ${clinic.details}. You can book, reschedule and cancel. Keep replies short.`, web_prompt: `You are the online assistant for ${clinic.name}. ${clinic.details}. If someone wants to book, tell them to call.`, speaking_rate: clinic.speaking_rate }) } ); ``` The changes take effect on the next call or text. This is how a 200-location rollout stays one agent + one PATCH per location - across calls, SMS, and web. ## Related * [SMS agent](/sms/sms-agent) - the `sms_prompt` + `sms_reply_enabled` feature * [Web agent](/web-assistant/overview) - the `web_prompt` feature * [Import phone number](/api-reference/phone-numbers/import) * [Voices](/concepts/voices) - the `voice_id` and `speaking_rate` settings * [Keypad input](/advanced/keypad-input) - the `dtmf_enabled` setting * [Call recording](/advanced/call-recording) - the `record_call` setting