What is the difference between AgentPhone and Inkbox?

AgentPhone supports 44 of the 77 features compared here, and Inkbox supports 45. AgentPhone adds group name and photo, chat backgrounds, WhatsApp, local testing and no-code integrations. Inkbox adds read receipts, shared numbers, line pooling, calls on the iMessage number and Slack.

Does Inkbox support group name and photo?

Inkbox does not list group name and photo on its site or in its docs.

Does Inkbox support chat backgrounds?

Inkbox does not list chat backgrounds on its site or in its docs.

Does Inkbox support WhatsApp?

Inkbox does not support WhatsApp.

AgentPhone vs Inkbox

Q: How much do AgentPhone and Inkbox cost?

AgentPhone: Pay as you go with $5 of starting credit: $3 per number a month, $0.13 to $0.22 a voice minute and $0.02 per SMS segment, with iMessage lines at $150 or $250 a month and no per-message charge. Inkbox: Free covers 3 identities with shared iMessage; Developer is $25 a month with a VoIP number; Startup is $167 a month with one dedicated iMessage number; Enterprise is custom. SMS/MMS and call minutes over allowance cost $0.03 each.

Compare AgentPhone and Inkbox side by side: iMessage features, channels, developer tools, pricing and compliance, checked on each provider's own site.

AgentPhone

Phone numbers with voice, SMS and iMessage for AI agents

Starting price: $3/month per number plus usage; iMessage from $150/month per line
Free plan: $5 starting credit, no card required

Visit AgentPhone Read more

Inkbox

Email, phone, iMessage and A2A identity for AI agents

Starting price: $25/month (Developer); $167/month for a dedicated iMessage number (Startup)
Free plan: Free: 3 identities, shared iMessage up to 2,000 messages a month and 3 recipients at a time

Visit Inkbox Read more

AgentPhone supports 44 of the 77 features compared here, and Inkbox supports 45.

Where AgentPhone is ahead

and 1 more in the table below.

Where Inkbox is ahead

and 2 more in the table below.

Feature comparison

Feature	AgentPhone	Inkbox
iMessage messaging
iMessage	SupportediMessage lines are a separate number type (type=imessage).	SupportedShared router service on every plan, or a dedicated line from the Startup plan.
Group chats	SupportediMessage groups arrive as one conversation with roster and sender; reply to the group id.	SupportedDedicated lines only, 2 to 8 remote participants. Shared service is 1:1.
Group management	PartialStart a new group by listing recipients and rename it; adding or removing members is not documented.	PartialCreate a group by sending to 2 to 8 numbers. No add or remove member API in V1.
Group name and photo	PartialGroup name can be set by API; the group icon is only readable.	Not listed
Mentions	Not listed	Not listed
Tapbacks	SupportedSix classic tapbacks, custom emoji on newer lines; inbound reactions via agent.reaction.	SupportedSend, replace and remove 7 tapbacks including eyes; inbound tapbacks arrive by webhook.
Threaded replies	Supportedreply_to_message_id; also on WhatsApp.	Supportedreply_to_message_id in 1:1 and group chats, with thread reads. Falls back to a plain reply.
Typing indicators	SupportedSend only, best-effort, auto-expires after a few seconds.	PartialSend only, in 1:1 chats. Groups and inbound typing events are not supported.
Read receipts	Not listedThe pricing page mentions read receipts; no API or webhook for them is documented.	PartialSend read receipts in 1:1 chats. No read status for your own sent messages is documented.
Edit and unsend	Not listed	Not listed
Message effects	Supported12 screen and bubble effects via send_style.	Supported4 bubble and 9 full-screen send styles, in 1:1 and dedicated-line groups.
Animated text effects	Not listed	Not listed
Stickers	Not listed	Not listed
Formatted text	Not listed	Not listed
Attachments	SupportedImages, video and files by URL; several images arrive as a carousel on iMessage.	SupportedOne media item per message, uploads up to 10 MiB. No media before the recipient's first reply.
Live Photos	Not listed	Not listed
Rich link previews	Not listed	Not listed
Voice messages	Not listed	Not listed
Contact cards	SupportedvCard files can be sent as media (listed as a supported MMS type).	PartialThe router sends the agent's contact card on connect. Sending other vCards is not documented.
Polls	Not listed	Not listed
Chat backgrounds	SupportedSet or remove a background image per iMessage conversation.	Not listed
Location sharing	Not listedThe API has location endpoints returning coordinates per number, but their use is not described.	Not listed
iMessage apps	Not listed	Not listed
Live app cards	Not listed	Not listed
Sender name and photo	PartialContact card sets a display name and avatar on the iMessage number; $250/month line only.	SupportedDedicated lines share the identity's display name and avatar automatically.
FaceTime calls	Not listed	Not listedCalls run over iMessage lines, but the docs do not say whether they are FaceTime.
Delivery status	PartialMessages carry a status and failure reason; no delivery or read webhooks are documented.	Supportedimessage.sent, imessage.delivered and imessage.delivery_failed webhooks, per recipient in groups.
iMessage availability check	SupportedLive check of iMessage, SMS and RCS reachability for a number before sending.	SupportedReturns iMessage, SMS or RCS for any E.164 number.
Focus and Notify Anyway	Not listed	Not listed
Numbers and delivery
Managed lines	SupportediMessage lines are ordered through the API and run by AgentPhone.	SupportedShared router lines and dedicated lines run by Inkbox. No Mac needed.
Dedicated numbers	SupportedUS and Canada numbers at $3/month; dedicated iMessage lines at $250/month.	SupportedStartup plan includes one dedicated iMessage number. VoIP numbers for calls and SMS from Developer.
Shared numbers	Not listed	SupportedFree and paid plans include shared iMessage. The human must text the router first.
Bring your own number	Not listed	Not listed
Line pooling	Not listed	BetaOrganization-owned shared iMessage pools, beta and by request only.
SMS fallback	SupportedFalls back to SMS/MMS when iMessage is not available.	SupportedInkbox tries iMessage first and can fall back to SMS; was_downgraded marks it.
RCS fallback	SupportediMessage-capable numbers deliver over RCS or SMS to non-Apple recipients.	PartialDocs describe SMS fallback, and the service field can report rcs. The transport cannot be chosen.
Outbound-first messaging	PartialOutbound iMessage lines: 50 new contacts a day per line; inbound-only lines do not start chats; SMS needs 10DLC.	PartialDedicated lines can start chats, up to 40 new recipients a day. Shared service needs the human to text first.
Calls on the iMessage number	Not listed	SupportedAgents place and receive voice calls over shared and dedicated iMessage lines.
Other channels
SMS	SupportedSMS and MMS; inbound works at once, outbound needs 10DLC.	SupportedSMS and MMS on dedicated VoIP numbers, US and Canada included. Group MMS is beta.
RCS	BetaRCS Business Messaging is beta and concierge-onboarded: branded sender, quick-reply chips.	PartialOnly as a transport reported on iMessage lines; not a channel you can pick.
WhatsApp	BetaBeta, enabled per account. Connect your own WhatsApp Business Account; Meta bills you.	Not supportedNot offered
Telegram	Not supportedNot offered	Not supported
Slack	Not supported	BetaSlack is in beta: read, reply, files and retained history search.
Email	Not supported	SupportedEach identity gets a mailbox, with custom domains and IMAP/SMTP access.
Phone calls	SupportedInbound and outbound calls in webhook mode or hosted AI mode; also browser web calls.	SupportedInbound and outbound calls with your own WebSocket agent or Inkbox Voice AI (beta).
Apple Messages for Business	Not supportedNot offered	Not supportedNot offered
Unified channel API	SupportedOne send endpoint for SMS, MMS, iMessage, RCS and WhatsApp; one agent.message webhook incl. voice.	PartialOne identity and one webhook subscription across channels, but separate APIs per channel.
Developer tools
REST API	Supported	Supported
TypeScript SDK	Supportednpm install agentphone	Supported@inkbox/sdk
Python SDK	Supportedpip install agentphone	Supportedinkbox on PyPI
Other SDKs	Not listedDocs list only TypeScript and Python; an agentphone-go repo holds only a placeholder README.	SupportedRust SDK (inkbox crate).
CLI	Not listedNo own CLI found; numbers can be provisioned through the Stripe Projects CLI.	Supported@inkbox/cli
Webhooks	SupportedProject default webhook with per-agent overrides.	Supported
Signed webhooks	SupportedHMAC-SHA256 over timestamp and body, with a timestamp header for replay protection.	SupportedHMAC-SHA256 with a per-identity signing key.
MCP server	SupportedHosted MCP server (mcp.agentphone.ai) and npm package agentphone-mcp.	SupportedRemote Streamable HTTP endpoint at inkbox.ai/mcp, with a separate ChatGPT endpoint.
Open source	Not supportedClosed platform. The MCP server and framework integrations are MIT-licensed on GitHub.	PartialSDK, CLI, skills and examples are MIT on GitHub. The service is closed.
Self-hosting	Not supportedHosted cloud service only	Not listed
Local testing	PartialBrowser web calls test a voice agent without a phone number; no message simulator found.	Not listed
Custom channel providers	Not listed	Not listed
Event replay	PartialFailed webhooks retry 5 times over about 20 hours; deliveries can be listed but not replayed.	SupportedDelivery log with replay. Incoming-call and Slack deliveries cannot be replayed.
OpenTelemetry	Not listed	Not listed
No-code integrations	PartialAgentPhone block in Sim's no-code workflow builder; no Zapier, Make, n8n or GoHighLevel found.	Not listed
CRM integrations	Not listed	Not listed
Built for AI agents
Agent framework	SupportedHosted voice mode runs calls from a system prompt; conversation state rides along in webhooks.	PartialIdentity layer with contact memories across email, texts and calls. No conversation framework.
Agent framework integrations	SupportedVercel Chat SDK adapter, LangChain, CrewAI and OpenAI Agents SDK tools, Google ADK guide.	SupportedPlugins for Hermes Agent, OpenClaw, OpenCode, Codex, Claude Code and DeepSeek Harness.
Streaming replies	PartialVoice only: NDJSON streamed webhook replies start speech on the first chunk.	Not listed
Agent group chats	PartialAgents can create and take part in iMessage groups; agent-to-agent groups are not described.	Not listedAgents can reach each other over A2A tasks, but not in group chats.
Human handoff	PartialVoice only: cold transfer of a call to a transferNumber, by the AI or your webhook.	PartialPeople can reply from the Console, and Voice AI can transfer a call. No handoff controls for agents.
Audit logs	Not listed	Not listed
Message history API	SupportedConversations with paginated messages and custom metadata; call transcripts.	SupportedList and read conversations and threads, with search on texts and email.
Plans and compliance
Free plan	Partial$5 starting credit, no card. Outbound calls need a top-up first.	SupportedFree: 3 identities, shared iMessage up to 2,000 messages a month and 3 recipients at a time.
Public pricing	Supported	Supported
No per-message fees	PartialiMessage lines and WhatsApp have no per-message charge; SMS is $0.02 a segment, MMS $0.03.	PartialiMessage is capped per plan with no per-message fee. Extra SMS/MMS and call minutes cost $0.03 each.
Uptime SLA	Not supportedTerms promise no uptime; SLAs only if set in an order or separate agreement.	Not listed
Isolated infrastructure	Not listedSub-accounts isolate agents, numbers and data per client; no dedicated infrastructure offer found.	PartialDedicated iMessage infrastructure is listed for Enterprise only.
SOC 2 Type II	PartialSOC 2 Type I report as of July 30, 2026; Type II examination in progress.	Not listed
GDPR	SupportedPrivacy policy sets out GDPR legal bases for processing.	Not listedThe DPA names the CCPA only; GDPR is not mentioned.

Feature

AgentPhone

Inkbox

iMessage messaging

iMessage

iMessage lines are a separate number type (type=imessage).

Shared router service on every plan, or a dedicated line from the Startup plan.

Group chats

iMessage groups arrive as one conversation with roster and sender; reply to the group id.

Dedicated lines only, 2 to 8 remote participants. Shared service is 1:1.

Group management

PartialStart a new group by listing recipients and rename it; adding or removing members is not documented.

PartialCreate a group by sending to 2 to 8 numbers. No add or remove member API in V1.

Group name and photo

PartialGroup name can be set by API; the group icon is only readable.

Not listed

Mentions

Not listed

Tapbacks

Six classic tapbacks, custom emoji on newer lines; inbound reactions via agent.reaction.

Send, replace and remove 7 tapbacks including eyes; inbound tapbacks arrive by webhook.

Threaded replies

reply_to_message_id; also on WhatsApp.

reply_to_message_id in 1:1 and group chats, with thread reads. Falls back to a plain reply.

Typing indicators

Send only, best-effort, auto-expires after a few seconds.

PartialSend only, in 1:1 chats. Groups and inbound typing events are not supported.

Read receipts

Not listedThe pricing page mentions read receipts; no API or webhook for them is documented.

PartialSend read receipts in 1:1 chats. No read status for your own sent messages is documented.

Edit and unsend

Not listed

Message effects

12 screen and bubble effects via send_style.

4 bubble and 9 full-screen send styles, in 1:1 and dedicated-line groups.

Animated text effects

Not listed

Stickers

Not listed

Formatted text

Not listed

Attachments

Images, video and files by URL; several images arrive as a carousel on iMessage.

One media item per message, uploads up to 10 MiB. No media before the recipient's first reply.

Not listed

Not listed

Not listed

vCard files can be sent as media (listed as a supported MMS type).

PartialThe router sends the agent's contact card on connect. Sending other vCards is not documented.

Polls

Not listed

Chat backgrounds

Set or remove a background image per iMessage conversation.

Not listed

Location sharing

Not listedThe API has location endpoints returning coordinates per number, but their use is not described.

Not listed

iMessage apps

Not listed

Live app cards

Not listed

Sender name and photo

PartialContact card sets a display name and avatar on the iMessage number; $250/month line only.

Dedicated lines share the identity's display name and avatar automatically.

FaceTime calls

Not listed

Not listedCalls run over iMessage lines, but the docs do not say whether they are FaceTime.

Delivery status

PartialMessages carry a status and failure reason; no delivery or read webhooks are documented.

imessage.sent, imessage.delivered and imessage.delivery_failed webhooks, per recipient in groups.

iMessage availability check

Live check of iMessage, SMS and RCS reachability for a number before sending.

Returns iMessage, SMS or RCS for any E.164 number.

Focus and Notify Anyway

Not listed

Numbers and delivery

Managed lines

iMessage lines are ordered through the API and run by AgentPhone.

Shared router lines and dedicated lines run by Inkbox. No Mac needed.

Dedicated numbers

US and Canada numbers at $3/month; dedicated iMessage lines at $250/month.

Startup plan includes one dedicated iMessage number. VoIP numbers for calls and SMS from Developer.

Shared numbers

Not listed

Free and paid plans include shared iMessage. The human must text the router first.

Bring your own number

Not listed

Line pooling

Not listed

BetaOrganization-owned shared iMessage pools, beta and by request only.

SMS fallback

Falls back to SMS/MMS when iMessage is not available.

Inkbox tries iMessage first and can fall back to SMS; was_downgraded marks it.

RCS fallback

iMessage-capable numbers deliver over RCS or SMS to non-Apple recipients.

PartialDocs describe SMS fallback, and the service field can report rcs. The transport cannot be chosen.

Outbound-first messaging

PartialOutbound iMessage lines: 50 new contacts a day per line; inbound-only lines do not start chats; SMS needs 10DLC.

PartialDedicated lines can start chats, up to 40 new recipients a day. Shared service needs the human to text first.

Calls on the iMessage number

Not listed

Agents place and receive voice calls over shared and dedicated iMessage lines.

Other channels

SMS

SMS and MMS; inbound works at once, outbound needs 10DLC.

SMS and MMS on dedicated VoIP numbers, US and Canada included. Group MMS is beta.

RCS

BetaRCS Business Messaging is beta and concierge-onboarded: branded sender, quick-reply chips.

PartialOnly as a transport reported on iMessage lines; not a channel you can pick.

BetaBeta, enabled per account. Connect your own WhatsApp Business Account; Meta bills you.

Not supportedNot offered

Not supported

Slack

Not supported

BetaSlack is in beta: read, reply, files and retained history search.

Not supported

Each identity gets a mailbox, with custom domains and IMAP/SMTP access.

Phone calls

Inbound and outbound calls in webhook mode or hosted AI mode; also browser web calls.

Inbound and outbound calls with your own WebSocket agent or Inkbox Voice AI (beta).

Apple Messages for Business

Not supportedNot offered

Unified channel API

One send endpoint for SMS, MMS, iMessage, RCS and WhatsApp; one agent.message webhook incl. voice.

PartialOne identity and one webhook subscription across channels, but separate APIs per channel.

Developer tools

REST API

TypeScript SDK

npm install agentphone

@inkbox/sdk

Python SDK

pip install agentphone

inkbox on PyPI

Other SDKs

Not listedDocs list only TypeScript and Python; an agentphone-go repo holds only a placeholder README.

Rust SDK (inkbox crate).

CLI

Not listedNo own CLI found; numbers can be provisioned through the Stripe Projects CLI.

@inkbox/cli

Webhooks

Project default webhook with per-agent overrides.

Signed webhooks

HMAC-SHA256 over timestamp and body, with a timestamp header for replay protection.

HMAC-SHA256 with a per-identity signing key.

MCP server

Hosted MCP server (mcp.agentphone.ai) and npm package agentphone-mcp.

Remote Streamable HTTP endpoint at inkbox.ai/mcp, with a separate ChatGPT endpoint.

Open source

Not supportedClosed platform. The MCP server and framework integrations are MIT-licensed on GitHub.

PartialSDK, CLI, skills and examples are MIT on GitHub. The service is closed.

Self-hosting

Not supportedHosted cloud service only

Not listed

Local testing

PartialBrowser web calls test a voice agent without a phone number; no message simulator found.

Not listed

Custom channel providers

Not listed

Event replay

PartialFailed webhooks retry 5 times over about 20 hours; deliveries can be listed but not replayed.

Delivery log with replay. Incoming-call and Slack deliveries cannot be replayed.

OpenTelemetry

Not listed

No-code integrations

PartialAgentPhone block in Sim's no-code workflow builder; no Zapier, Make, n8n or GoHighLevel found.

Not listed

CRM integrations

Not listed

Built for AI agents

Agent framework

Hosted voice mode runs calls from a system prompt; conversation state rides along in webhooks.

PartialIdentity layer with contact memories across email, texts and calls. No conversation framework.

Agent framework integrations

Vercel Chat SDK adapter, LangChain, CrewAI and OpenAI Agents SDK tools, Google ADK guide.

Plugins for Hermes Agent, OpenClaw, OpenCode, Codex, Claude Code and DeepSeek Harness.

Streaming replies

PartialVoice only: NDJSON streamed webhook replies start speech on the first chunk.

Not listed

Agent group chats

PartialAgents can create and take part in iMessage groups; agent-to-agent groups are not described.

Not listedAgents can reach each other over A2A tasks, but not in group chats.

Human handoff

PartialVoice only: cold transfer of a call to a transferNumber, by the AI or your webhook.

PartialPeople can reply from the Console, and Voice AI can transfer a call. No handoff controls for agents.

Audit logs

Not listed

Message history API

Conversations with paginated messages and custom metadata; call transcripts.

List and read conversations and threads, with search on texts and email.

Plans and compliance

Free plan

Partial$5 starting credit, no card. Outbound calls need a top-up first.

Free: 3 identities, shared iMessage up to 2,000 messages a month and 3 recipients at a time.

Public pricing

No per-message fees

PartialiMessage lines and WhatsApp have no per-message charge; SMS is $0.02 a segment, MMS $0.03.

PartialiMessage is capped per plan with no per-message fee. Extra SMS/MMS and call minutes cost $0.03 each.

Uptime SLA

Not supportedTerms promise no uptime; SLAs only if set in an order or separate agreement.

Not listed

Isolated infrastructure

Not listedSub-accounts isolate agents, numbers and data per client; no dedicated infrastructure offer found.

PartialDedicated iMessage infrastructure is listed for Enterprise only.

SOC 2 Type II

PartialSOC 2 Type I report as of July 30, 2026; Type II examination in progress.

Not listed

GDPR

Not listedThe DPA names the CCPA only; GDPR is not mentioned.

Checked on each provider's own site and docs on 2026-10-25. “Not listed” means the provider does not mention it.

Pricing

AgentPhone

Pay as you go with $5 of starting credit: $3 per number a month, $0.13 to $0.22 a voice minute and $0.02 per SMS segment, with iMessage lines at $150 or $250 a month and no per-message charge.

Pricing model: usage-based, flat per line for iMessage

Source

Inkbox

Free covers 3 identities with shared iMessage; Developer is $25 a month with a VoIP number; Startup is $167 a month with one dedicated iMessage number; Enterprise is custom. SMS/MMS and call minutes over allowance cost $0.03 each.

Pricing model: monthly plans with allowances, plus per-unit SMS/MMS and call-minute overage

Source