TwinPhone vs MarkupBase

A side-by-side comparison built from both listings. Blank cells mean the company has not given that detail; we never guess.

TwinPhone compared with MarkupBase
Detail	TwinPhone	MarkupBase
What it does	Browser-based international calling service with pay-per-minute rates to 145+ countries	Review Markdown and HTML with people and AI agents
Stage	Not given	Not given
Founded	2022	Not given
Based in	CZ	US
Pricing model	Not given	Not given
Pricing	Calls: $0.02/min to US and Canada, $0.06–$0.12/min to UK, $0.08/min to India, rates for other countries shown before dialling. Virtual numbers: from $3.19/month for US, Canada or Puerto Rico numbers. Receiving calls: $0.02/min from balance. Minimum top-up: $10. Billed per minute, rounded up, with 60	Free plan: $0 with 25 artifacts (including 5 private), 250 MB storage, 1 active agent connection, 500 MCP write actions per month. Pro plan: $120/year (or $12/month) with 1,000 artifacts, 10 GB storage, 20 active agent connections, 25,000 MCP write actions per month. Enterprise pricing available by
Key features	Call 145+ countries from web browser No app, SIM card or contract required Transparent per-minute pricing shown before call Encrypted calls with TLS and SRTP Adaptive audio for unstable connections Virtual US and Canada numbers for receiving calls and SMS Call history and contacts storage Enterprise plan with shared wallet and analytics Works on iOS and Android apps Balance never expires	Versioned Markdown and HTML artifacts Contextual comments and immutable review history Review requests for people and AI agents Model Context Protocol (MCP) integration Safe HTML previews Permanent version history with revision tracking Private, unlisted, and public artifact visibility Support for multiple active agent connections Isolated preview for untrusted HTML Separate identities for people and agents
What makes it different	Pay only for calls you make with transparent per-minute rates, no subscriptions or hidden fees Works in any modern browser without installing apps or requiring SIM cards Calls maintained on poor Wi-Fi with adaptive audio codec adjustment All calls encrypted in transit with industry-standard encryption Replace Skype with browser-based alternative after Skype shutdown in May 2025	Immutable review history keeps every decision alongside the work MCP integration enables reliable agent handoffs without custom tool connections Humans retain final approval authority while agents work autonomously Comments carry forward across versions showing what changed and why Works across multiple agent systems and between agents and people over time
Free plan	Not given	Not given
Open source	Not given	Not given
Platforms	Not given	Not given
Public API	Not given	Not given
Community votes	0	0
DR (Domain Rating by Ahrefs)	22 +2 (up) since last check	7 −1 (down) since last check
Trust Flow (Majestic)	15	0
Citation Flow (Majestic)	27	26
Referring domains (Majestic)	69	31

5 details filled in for both companies.

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