Grandstream gxp1628 will not work with specific extensions

Strange issue with a specific extension. Extension 21174 can register using a sip soft phone, but cannot register with a grandstream gxp1628.
I have tried 21174 extension on two gxp1628’s. Other accounts work perfectly with the gxp1628’s.
while running asterisk -rvvv I see the following message repeating endlessly.

Added contact ‘sip:[email protected]:36892’ to AOR ‘21174’ with expiration of 3600 seconds

I opened a ticket with grandstream and after a trace they said the following.

“From the trace your PBX is sending no binding sip OK message with expires 0, after receiving sip registration request from the GXP1628. The PBX should send at least sip challenge message 401.
You can remove the extension and create it again perhaps this could solve the issue.”

I have recreated the extension several times but still this is the case.

Well, got this one figured out finally.
As expected there was an issue within the asterisk database, specifically the astdb.sqlite3 found in
Here is what I did to fix.
1 Removed 21174 from the extensions; saved config
2 Copied astdb to local machine, opened it with sqliteman and ran these select statement
3 Inside sqliteman ran the two following DELETE statements
DELETE1 = “delete From astdb where key like ‘%21174%’;
DELETE2 = “delete From astdb where value like ‘%21174%’;”
4 stopped asterisk with amportal stop
5 renamed current astdb.sqlite3 for safe keeping
6 copied back edited astdb.sqlite3
7 chmod’d the database to asterisk:asterisk
8 amportal start; problem fixed.