Failed to authenticate Cisco SIP device

I am working on this issue but I am new to Asterisk.
We were asked to add Cisco phones (CP-8851) to the Asterisk PBX (v We are also using SoliCall pbxmate. When trying to conference with Cisco phones in a filtered conference, the warnings below appear and the phones are not in a filtered conference (with Solicall).
[Jun 19 14:31:26] WARNING[27077]: chan_sip.c:14992 check_auth: username mismatch, have <6100>, digest has <SoliCallPairA_2>
[Jun 19 14:31:26] NOTICE[27077]: chan_sip.c:23575 handle_request_invite: Failed to authenticate device “CISCO EXEC” sip:6100@;tag=46803848500
[Jun 19 14:31:26] WARNING[27077]: chan_sip.c:21116 handle_response_invite: Received response: “Forbidden” from ‘“CISCO EXEC” sip:6100@;tag=as14155737’

Any ideas will be appreciated.

What happens when you address the first error, which is clearly described by the error message.

The only hint I found was to set “secret=” in which case the error does not show. However I end up with an additional filtered (solicall) connection to the device, as well as an unfiltered connection.
I am assuming that Asterisk is sending the wrong user name to the SIP device when trying to conference with SoliCall. I think it is a code issue, not a dial plan issue, tracing through the code.

This is the very heavy hint.