Softstringsphone

Maikstrings

About this app

Softstringsphone turns your Android phone into a telephone of your FRITZ!Box. Call with your own landline number, get called just like on a cordless phone, and always have the box's call list and phone book with you – at home on Wi-Fi and on the go via the built-in VPN.

EVERYTHING ON ONE SCREEN
• Dial pad always visible, with recent calls, favourites, the FRITZ!Box call list and phone book, and your phone's contacts above it
• Search as you type, by digits or names (T9)
• Long-press 0 for "+", paste numbers from the clipboard
• "Dial" and phone number links from other apps land in the dial pad

TAKE CALLS
• Incoming calls ring with ringtone and vibration, full screen even over the lock screen
• Missed calls are reported
• A sound and a red bar warn you when you can't be reached

TWO WAYS TO CALL
• SIP: as an IP phone on your FRITZ!Box or directly with a SIP provider
• CAPI: quick to set up via the FRITZ!Box CAPI interface on your home network
• Hide your number if you like, your own display name over SIP
• Emergency numbers 110 and 112 always without prefix code and with your number

SECURE
• SIP over TLS with certificate checks, voice encrypted with SRTP – a green padlock shows it during the call
• Passwords encrypted in the Android keystore
• No ads, no account, no data sharing: the app only talks to your FRITZ!Box or your SIP provider

ON THE GO LIKE AT HOME
• Built-in VPN to your own FRITZ!Box (WireGuard) – choose the box's settings file once, then a switch is all it takes
• After a phone restart the VPN comes back on by itself
• If the box's internet address changes, the app reconnects

EASY SETUP
• Step-by-step assistants for the IP phone on the FRITZ!Box and for the VPN, with a test at the end
• Try it without a FRITZ!Box: enter "demo" as the address

DURING A CALL
• Mute, speaker, keypad (DTMF), call duration
• The proximity sensor turns the screen off at your ear
• Light, dark, German and English, phone and tablet

REQUIREMENTS
• A FRITZ!Box with telephony – or any SIP account
• For CAPI: CAPI over TCP enabled on the box (dial #96*3* on a phone)
• On the go with the FRITZ!Box: the box's WireGuard VPN (FRITZ!OS 7.50 or later)

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

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

What’s new

First release in the store:
• Calls through your FRITZ!Box via SIP or CAPI, with your landline number
• Take calls, even on the lock screen
• Encrypted with TLS + SRTP
• On the go via VPN to your FRITZ!Box with our app "Router VPN"
• Sound warning when you can't be reached
• Assistants for IP phone and VPN
• Sign out with or without deleting data