How to make SRV records work with caching resolvers?

[Peter]

My Telco has removed the A record for their VoIP server, and now has
only SRV data there - which seems not to work properly.

The SRV data contains various services (SIP via UDP, TCP, secure
TCP, whatever), and these get individual expiry counters in the
caching resolver.
So when a telephone sends a query, the caching resolver will provide
that data in the "Additional section" - but only those records that
have not yet expired. 

If the configured service (the one the telephone should use) is no
longer contained in the answer (but others are still present), the
telephone goes offline until all the records have expired and a new
authoritative query is made.

The Telco is of no help - they just want to sell their own equipment.

The telphones (Alcatel) are the usual linux plastic box, and I cannot
easily hack these. It probably does not behave fully correct, but
also not fully wrong.

In BIND/named I didn't find an easy approach to fix the issue - it
doesn't look like it is supposed to be fixed there. And before I go
for the more difficult approaches, I would like to ask how this
is actually supposed to work, at all.


-- PMc