Based on this product's specifications, here are some alternatives and similar models
Replacement Li-Pol 350 mAh battery for MITEL MiVoice 6930 IP Phone
Summary description:
Rechargeable Li-Pol battery with 350 mAh capacity designed as a replacement for the MITEL MiVoice 6930 IP Phone. Provides backup power for handset functions and improves call continuity when installed. Compatible with the specified model for straightforward swap-in replacement. Useful for restoring battery life in office phones and ensuring reliable daily operation.