Signal House vs Linq

Signal House supports 24 of the 77 features compared here, and Linq supports 63.

Feature comparison

Feature	Signal House	Linq
iMessage messaging
iMessage	Not supportedNo iMessage support	Supported
Group chats	Not supported	SupportedPro plan. Up to 31 recipients. No read or delivery receipts in groups.
Group management	Not supported	SupportedAdd and remove participants and leave a group, iMessage groups only, 3-member minimum.
Group name and photo	Not supported	SupportedSet display_name and group_chat_icon on group chats.
Mentions	Not supported	SupportedGroup chats only. Notifies iMessage recipients even in a muted chat.
Tapbacks	Not supported	SupportedSix classic tapbacks or any emoji, send and receive via reaction webhooks.
Threaded replies	Not supported	Supportedreply_to with optional part_index. iMessage only.
Typing indicators	Not supported	SupportedSend and receive, in direct and group chats. iMessage only.
Read receipts	Not supported	SupportedMark chats read and receive message.read. One-to-one chats only.
Edit and unsend	Not supported	PartialEdit text up to 5 times within 15 minutes. Delete does not unsend from the recipient's device.
Message effects	Not supported	Supported11 screen and 4 bubble effects.
Animated text effects	Not supported	Supportedtext_decorations animations: big, small, shake, nod, explode, ripple, bloom, jitter.
Stickers	Not supported	SupportedPeel emoji or images onto messages, send stickers, or place them inline in text.
Formatted text	Not supported	SupportedBold, italic, underline and strikethrough ranges, plus animated text. iMessage only.
Attachments	Not supported	SupportedUp to 10MB by URL, 100MB with pre-upload.
Live Photos	Not supported	Not listed
Rich link previews	Not supported	Supportedlink parts render as rich previews on iMessage and RCS.
Voice messages	Not supported	SupportedDedicated voice memo endpoint renders the native iMessage voice bubble.
Contact cards	Not supported	SupportedSend .vcf files as media parts.
Polls	Not supported	SupportedCreate, add options, vote and read tallies, with poll webhooks. Not as a chat's first message.
Chat backgrounds	Not supported	SupportedColor, animated or photo backgrounds, in direct and group chats.
Location sharing	Not supported	SupportedRequest, read and stop Find My shares. Live location is a $79/mo add-on on Pro.
iMessage apps	Not supported	SupportedPro plan. Cards from your own Messages extension, or Linq-hosted cards (Experiences).
Live app cards	Not supported	SupportedUpdate App Card replaces a delivered iMessage app or Experience card in place.
Sender name and photo	Not supported	SupportedContact card API sets name and photo, shared per chat via Name and Photo Sharing.
FaceTime calls	Not supported	Not supportedDocs say the API does not place or answer calls.
Delivery status	Not supported	Supportedsent, delivered, read and failed webhooks. Groups report sent only.
iMessage availability check	Not supported	Supportedcheck_imessage and check_rcs endpoints.
Focus and Notify Anyway	Not supported	Not listed
Numbers and delivery
Managed lines	Not supportedNo iMessage support	Supported
Dedicated numbers	SupportedLocal 10DLC and toll-free numbers at $1.00/month, plus short codes	SupportedPaid lines are dedicated. Provisioned by Linq, no self-serve number API.
Shared numbers	Not listed	SupportedFree Hobby tier uses a Shared Line, inbound-first, 20 contacts.
Bring your own number	SupportedPort-in requests by API, handled by staff; llms.txt also lists BYON	Not listed
Line pooling	Not listed	SupportedManaged load balancing (Pro): send without from and Linq picks and fails over lines.
SMS fallback	Not supportedNo iMessage support	Supported
RCS fallback	Not supported	SupportedOrder is iMessage, then RCS, then SMS.
Outbound-first messaging	SupportedSends from numbers on an approved 10DLC campaign	SupportedFree Hobby tier is inbound-first. Docs recommend inbound-first flows to avoid flagging.
Calls on the iMessage number	Not supportedNo iMessage support	PartialAPI forwards inbound calls on the line; outbound needs caller-ID masking via another provider.
Other channels
SMS	SupportedSMS, MMS and group messages on 10DLC, toll-free and short code, North America	Supported
RCS	Not supportedOn the roadmap (Coming Soon page)	Supported
WhatsApp	Not supported	BetaSeparate WhatsApp API in beta. Access by request, no SLA.
Telegram	Not supportedNot offered	Not supportedNot offered
Slack	Not supportedNot offered as a channel; support runs in Slack	Not supported
Email	Not supportedNot offered	Not supportedNot offered. iMessage can be sent to Apple ID email handles.
Phone calls	SupportedProgrammable calls, WebRTC softphone tokens, SIP trunks and call logs	PartialAPI does not place or answer calls; it forwards inbound calls. Calling lives in the Linq Blue app.
Apple Messages for Business	Not supportedOn the roadmap (Coming Soon page)	Not listedAI context page mentions it, but no product page or docs were found.
Unified channel API	PartialSMS, MMS and group messages share the Messages API; voice is a separate service	PartialiMessage, RCS and SMS share one API. WhatsApp is a separate API with its own keys and SDKs.
Developer tools
REST API	Supported	Supported
TypeScript SDK	Supported@signalhousellc/sdk, with a webhook verifier	Supported@linqapp/sdk
Python SDK	Supportedsignalhouse on PyPI	Supportedlinq-python
Other SDKs	Supported.NET, Go, PHP, Ruby and Rust	SupportedOfficial Go SDK.
CLI	Not listed	Supported@linqapp/cli: signup, sending, and a local webhook listener.
Webhooks	SupportedMessage, campaign, number health and other events	Supported
Signed webhooks	SupportedHMAC-SHA256 over timestamp and body, with secret rotation	SupportedHMAC-SHA256, Standard Webhooks format, with replay protection.
MCP server	SupportedRemote MCP server with OAuth; sends SMS and MMS, buys numbers, registers campaigns	Supported@linqapp/sdk-mcp with docs search and code execution tools.
Open source	Not supportedClosed platform; SDKs are public on GitHub	PartialSDKs, CLI and adapters are Apache-2.0 or MIT on GitHub. The messaging platform is closed.
Self-hosting	Not supportedHosted service only	Not supportedLinq describes itself as fully managed, in contrast to self-hosted options.
Local testing	PartialPOST /agent/messages chats with a hosted agent over the API, no phone needed	Not listedThe CLI streams webhooks locally, but tests still use a real phone.
Custom channel providers	PartialHeld agent replies can be claimed and delivered through your own channel	Not listed
Event replay	PartialThree quick retries; missed messages can be re-read from the message log API	PartialRetries for 30 minutes; after that, re-fetch chats or ask Linq for a manual replay.
OpenTelemetry	Not listed	PartialW3C trace IDs on every response and webhook for OTel backends. No export of Linq spans by default.
No-code integrations	SupportedGoHighLevel app and Make.com	SupportedLinq Blue works as a GoHighLevel messaging provider. No n8n, Make or Zapier found for the API.
CRM integrations	SupportedNative HubSpot SMS and MMS app; Salesforce is on the roadmap	SupportedVia Linq Blue: GoHighLevel, HubSpot and Salesforce.
Built for AI agents
Agent framework	SupportedAgent profiles with tools, knowledge and per-channel settings for webchat, SMS and voice	PartialNo own framework. Maintains a Vercel Chat SDK adapter and OpenClaw and Hermes plugins.
Agent framework integrations	Not listed	SupportedLinq-maintained Vercel Chat SDK adapter, plus OpenClaw and Hermes Agent plugins.
Streaming replies	Not listed	Not supportedDocs say the Chat SDK adapter buffers streams into one final message.
Agent group chats	PartialGroup messages to several recipients from one 10DLC number; not agent-specific	Not listed
Human handoff	SupportedReview mode holds each agent reply as a draft for a person to approve, reject or claim	Not listed
Audit logs	Not listed	SupportedDashboard Activity page plus account-change webhooks with actor and origin.
Message history API	SupportedMessage logs with filters, plus stored agent conversations	Supported
Plans and compliance
Free plan	Partial$25 credit for new accounts	SupportedHobby: $0, up to 20 contacts, through the CLI.
Public pricing	Supported	SupportedPro from $260/mo. Enterprise is custom.
No per-message fees	Not supportedPer segment, plus carrier fees at cost	Supported
Uptime SLA	Not listed	SupportedContractual SLAs on the Enterprise plan; marketing cites 99.95%
Isolated infrastructure	Not listed	SupportedDedicated lines across 4 data centers on paid plans; Hobby uses a shared line
SOC 2 Type II	Not listed	SupportedType I and Type II, reports for 2022, 2024, 2025 and 2026.
GDPR	Not listed	SupportedDPA covers GDPR and UK GDPR, with Standard Contractual Clauses.

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

Pricing

Which should you choose?

Choose Signal House if you need bring your own number, local testing, custom channel providers and agent group chats.

Choose Linq if you need iMessage, group chats, group management and group name and photo.

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