We’re developing a call answering service for small businesses. When our customer is busy, phone calls to them would be forwarded to our business’s VoIP phone number instead of going to voicemail.
Busy call forwarding is supposedly supported by all US cellular infrastructures (Verizon, AT&T, T-Mobile).
So far, every Verizon/AT&T user we test with is able to set this up. But whenever we try setting this up with a T-Mobile user (or a mobile brand that operates on the T-Mobile network), setup either fails, or succeeds but then busy calls are not forwarded, or they sometimes are.
We have spent hours experimenting with different call forwarding and reset codes ourselves (*21, *61, *62, *67, 004, ##004#, etc) and on the phone with T-Mobile technical support, but so far have not figured out a clear set of setup instructions that always work reliably.
Has anyone else encountered this issue and knows how to address it? We would be willing to pay $250/hour to consult with an expert on this matter.
This puts T-Mobile under a negative light vs Verizon / AT&T, which is a real pity for them.
