res_rtp_asterisk.c:3559 ast_rtp_read: RTP Read too short

Hello, I have verbose set to 5 on my asterisk CLI and i am receiving constant messages as follows:

res_rtp_asterisk.c:3559 ast_rtp_read: RTP Read too short.

The PBX is on a public IP, and the phones are remote behind a NAT. We are using Aastra phones, does anyone know why I’m getting this error? We do not use it for faxing, and faxing is not enabled.

Thank you for your help