Softstringsphone Pro

Maikstrings

About this app

Softstringsphone Pro turns your Android phone into a handset for your FRITZ!Box – with a secretary that works only on your phone. Call with your landline number, read along during the call, get "who does what by when" notes afterwards, and let an assistant announce unknown callers first. No cloud, no account, no ads.

AI ON THE DEVICE
• Live captions during calls, both sides with speaker – with offline speech recognition (Android 13+) or the app's AI speech pack (older phones too)
• Live translation of the other party into your language (Android 12+, the device's offline translator)
• Call notes: reason, topics, tasks with owner and deadline, appointments, numbers, amounts – share them or add them to your calendar, stored encrypted
• Strictly local: only the system's offline services and the app's AI speech pack, no audio is ever stored
• The other party hears an announcement with the option to object – or, if you prefer, consents by pressing 1, with proof in the note

CALL SCREENING AND SPAM PROTECTION
• Unknown and hidden numbers are answered by the assistant first, which asks for name and reason
• You read along and decide: take over, decline, block – listen in at any time
• Robocalls, prize draws and scams are politely turned away and the number is blocked, on request in the FRITZ!Box too
• Key spam filter: callers who want to be connected press 1 – auto-dialers stay out
• Known numbers ring as usual

AUDIO
• Noise suppression for your voice (off, normal, strong), optionally for the other side too
• Opus with dynamic bitrate over SIP, error protection when switching from Wi-Fi to mobile data; otherwise G.711

FRITZ!BOX AT THE PUSH OF A BUTTON
• The app finds your FRITZ!Box by itself
• Add an IP phone with one tap, including two-factor confirmation on the box
• Edit the box's phone book, sync it with your phone, set call barring

OPEN FOR AUTOMATIONS
• Webhooks (HTTPS, optionally HMAC-signed) for Home Assistant, Node-RED, n8n or your CRM
• Broadcast for Tasker and MacroDroid, "Open in CRM" with your own link template

CALLING AS USUAL
• SIP (as an IP phone on the box or with a SIP provider) or CAPI on your home network
• Encrypted with TLS + SRTP, never falling back to unencrypted
• Incoming calls full screen, even over the lock screen
• Dial pad with T9 search, the box's call list and phone book, favourites, contacts
• On the go via VPN to your own FRITZ!Box – with our free app “Router VPN” (shows whether the VPN is on, opens the VPN app)

SECURE AND PRIVATE
• Passwords and notes encrypted with AES-256 in the Android keystore
• No ads, no analytics, no Google Play services, no server of ours

REQUIREMENTS
• A FRITZ!Box with telephony – or any SIP account
• Captions need Android 13+ with an offline language pack or the app's AI speech pack (downloaded in the app), translation Android 12+ with an offline language pack; for a call-assistant greeting with your name, an offline text-to-speech voice (otherwise built-in announcement)
• Try it without a FRITZ!Box: enter "demo" as the address

For emergency calls, your phone's mobile network is the more reliable route.

FRITZ!Box is a trademark of FRITZ! GmbH. Softstringsphone Pro is an independent project by Maikstrings and not a product of FRITZ! GmbH.

What’s new

First release of Softstringsphone Pro:
• Live captions (also with our own AI speech pack), translation and call notes – only on your phone
• Call screening with spam protection, optionally press 1 to connect
• Noise suppression, Opus with dynamic bitrate
• Find the FRITZ!Box, IP phone with one tap, phone book sync
• Webhooks, broadcast and CRM link
• Telephony core of Softstringsphone: SIP with TLS + SRTP, CAPI
• On the go via VPN with our app “Router VPN”