This is one feature I like with the grandstreams: if the SIP server supports 484 responses ("Incomplete Address"), the grandstream can be set to use the Early Dial feature, whereby every digit pressed results in sending an invite to the SIP server with the number collected so far. If the SIP server sends back a 484, the GS will keep collecting digits until it gets a success or failure response. This is nice since it doesn't require dialplan juju in the ATA and dialing 7 digits works instantly I have my asterisk server set up this way.