Based on this product's specifications, here are some alternatives and similar models
Battery for Snom M65/M85 TCP/IP phones — replacement battery (MPN 3932)
Summary description:
Replacement battery compatible with Snom M65 and M85 TCP/IP desk phones (MPN 3932). Designed to restore portable power functions for these phone models, it provides reliable handset/back-up power for business and office use. Easy to install as a direct replacement, it helps maintain uninterrupted VoIP communication and extends device usability.