FreePBX SIP error

Hello, sorry for writing in English here but can't find a support for my issue and am trying this forum.
I am using FreePBX server and configured several OVH lines as trunks. It was working perfect however recently it started reporting errors about invalid value in the header of a SIP message sent from OVH server.
The error is below:
[2019-05-08 11:58:22] ERROR[9332] pjproject: sip_parser.c Error parsing '4294967295': String value was greater than the maximum allowed value.
[2019-05-08 11:58:22] ERROR[9332] pjproject: sip_transport.c Error processing 407 bytes packet from UDP 91.121.129.20:5060 : PJSIP invalid value error exception when parsing 'Contact' header on line 3 col -1:
OPTIONS sip:s@178.xx.xxx.xxx:5060;line=krkdwyb SIP/2.0
Call-ID: 00-01136-10e655af-75e8b8f87@91.121.129.20
Contact: ;expires=4294967295
CSeq: 1 OPTIONS
From: ;tag=00-01136-10e655ae-65485c5e1
Max-Forwards: 70
To:
Via: SIP/2.0/UDP 91.121.129.20:5060;rport;branch=z9hG4bK-ZLJX-0a80effa-3d69d2f4
Content-Length: 0
-- end of packet.

Why OVH sends such a high value for contact expiry in these keepalive packets?
4294967295 is 2^32 and it represents 32bit unsigned integer, however FreePBX expects signed integer (in range -2^16 to 2^16)
How could i resolve this issue?
The phones are working good but logs are getting flooded with the error.