Five major Japanese electronics firms announced an agreement Wednesday to market video telephones especially for home use, allowing callers to see still images of the person on the other end of the line.

The companies said the agreement calls for them to produce equipment with standardized specifications so users can combine parts from different companies.

The five companies are Matsushita Communication Industrial Co., an affiliate of Matsushita Electric Industrial Co.; Mitsubishi Electric Corp.; NEC Corp.; Sanyo Electric Co.; and Sony Corp.

Unlike telephones which can transmit television-like pictures, the Japanese models transmit still pictures only. Because still video phones use existing home telephone lines, pictures cannot be transmitted during conversation.

One model currently in use allows the sender to pose, push a button and in a few seconds a still image will appear on the screen at the other end of the line. A new image can be sent about every 30 seconds.