11 min read
The best SSH clients in 2026 for Windows, macOS, Linux and Android
The best SSH client depends on your platform. We compare OpenSSH, PuTTY, MobaXterm, Termius and Tabby by platform, as of October 2026.
Blog
Practical guides on SIP, VoIP and running servers, and notes on how our products work. Newest first.
11 min read
How to connect a softphone to FreePBX or Asterisk (PJSIP), step by step
FreePBX softphone setup over PJSIP: create the extension, match the Asterisk endpoint, auth and aor config, set NAT options, and fix 401, 403 and timeouts.
10 min read
Introducing Darwvin Softphone: a SIP softphone that tells you why a call failed
Darwvin Softphone is a SIP softphone for Android and Linux, in Early Access. Its Call Doctor ranks the likely causes of a failed or bad-sounding call.
10 min read
Introducing RemoteOpsX: SSH, SFTP, tunnels and server health in one app
A MobaXterm alternative for Linux, RemoteOpsX puts SSH, SFTP, tunnels and server health in one desktop app. The Free plan covers up to three servers.
14 min read
SIP and NAT explained: STUN, TURN, ICE, rport and SIP ALG
SIP NAT traversal explained: why NAT breaks SIP calls, how rport, STUN, TURN and ICE help, why SIP ALG hurts, and the Asterisk PJSIP settings.
13 min read
SIP response codes explained: the complete reference with causes and fixes
SIP response codes from 1xx to 6xx with RFC 3261 meanings, the real causes of 401, 403, 480, 488 and 503, and how to fix each one.
11 min read
SIP trunks, hosted PBX and softphones: VoIP basics for small businesses
SIP trunk vs hosted PBX vs softphone for small businesses: what each one is, how they connect, what drives the cost and how to choose.
12 min read
The SSH config file: a practical guide to Host, ProxyJump, IdentityFile and more
The SSH config file explained: Host and Match precedence, ProxyJump bastions, IdentityFile, ControlMaster multiplexing, Include, and a full example.
13 min read
SSH keys done right: Ed25519 setup and login without a password
Create an Ed25519 key with ssh-keygen, install it with ssh-copy-id or by hand, fix authorized_keys permissions, load ssh-agent, then turn off password logins.
12 min read
Fix "Permission denied (publickey)" and "Host key verification failed"
Fix Permission denied (publickey) and Host key verification failed: read ssh -vvv output, check keys and permissions, sshd logs and known_hosts fingerprints.
11 min read
SSH port forwarding explained: local, remote and dynamic tunnels
SSH port forwarding explained with ssh -L, -R and -D: reach a private database, expose a dev server, run a SOCKS proxy, and keep tunnels alive.
10 min read
VoIP codecs compared: Opus vs G.711 vs G.722 vs G.729
VoIP codecs compared: Opus, G.711, G.722 and G.729 by bitrate and bandwidth per call with RTP overhead, licensing, packet loss and Asterisk codec order.
11 min read
One-way audio or no audio on VoIP calls: causes and step-by-step fixes
Fix one-way or no audio on VoIP calls by checking SDP addresses, SIP ALG, blocked RTP ports, symmetric RTP, codecs and hold, with captures and Asterisk fixes.
10 min read
Zoiper alternatives in 2026: SIP softphones for Android, desktop and Linux
Zoiper alternatives in 2026 compared by platform: Linphone, MicroSIP, Bria, Groundwire, Jami, Telephone and Blink for Android, Windows, macOS and Linux.