Official Zoiper website does host v2.43. Trusted archives (e.g., oldapps.com, majorgeeks.com) may have it with MD5 checksums. Always scan any old executable with VirusTotal before use.
is a legacy softphone application for Windows, developed by Securax Ltd. (now Zoiper). It was the last version of the "Classic" freeware line before Zoiper shifted to a freemium model with Zoiper Business/Lite. i--- Zoiper Classic 2.43 Download
Searching for "I--- Zoiper Classic 2.43 download" indicates a specific need—likely nostalgia, legacy hardware support, or avoiding software bloat. Official Zoiper website does host v2