Can't write frame?

hello all i keep getting an occasional message on the console of our asterisk box

[Jan 15 14:51:44] WARNING[5833]: chan_sip.c:3606 sip_write: Can’t send 22799936 type frames with SIP write
> Channel SIP/1210-015d7560 was answered.

its asterisk version

i dont think its affecting any calls although i will check on this with our agents

i’ve googled this an there doesnt really seem to be much about regarding it?

thanks all