Multiple agents answer the same call

Hello,
I am having the issue with multiple answers of the same call.
for example we have two agents A and B and the single call from the customer say Tom come and goes to A and B and both A and B talk.so we want to avoid this issue and want only A or B need to attend the call not the both.
for the incoming calls from IAX. I have the following settings
[incoming-calls]
s, 1, Dial(sip/A&sip/B)
s,2,hangup

The sip settings contains
[A]
deny=0.0.0.0/0.0.0.0
type=friend
secret=200
qualify=yes
port=5060
pickupgroup=
permit=0.0.0.0/0.0.0.0
nat=yes
mailbox=A@device
host=dynamic
dtmfmode=rfc2833
dial=SIP/A
context=from-internal
canreinvite=no
callgroup=
callerid=device
accountcode=
call-limit=50

Without a conference, there is no way that Asterisk can sensibly have two people answer one call.

If your description is correct, and you are using a supported version (no supported version understands canreinvite - they expect directmedia) you should provide SIP debugging traces. You will need to provide these if you want to report a bug, officially. (Supported versions are 1.8.x and 1.10.x.)

Dial should abort the call to the other agent when one answers.

First time i hear asterisk allow answer the same call by two different extensions (phones,etc.)

Are you sure that is happening?

Using Dial(SIP/A&SIP/B) both A and B will Ring… but the call is only answer by the first one who take the call from handset, speaker, pickup,etc…

Imagine an incoming call, if phone B answer the call, the phone A will stop ring… and when phone A take the handset or speaker, he will hear Dial tone.

Hope my opinion make you more clear now…

Thanks! guys the software team at my office embedded the zoiper web version into our call center app. They enable the auto answer. But they were not willing to accept theirs bug therefore on my research I posted this and after disabling the auto answer. It work fine now
thank you again.