Multiphone and IP PBX - do you have all incoming calls going to IP PBX?

Question

Telephony

Some time ago, our online store (Peter) began to miss the only city telephone number from Megafon and normal office telephone communications. In order not to bother with servers / asterisks / admins, we decided to outsource the task and turn to providers of ready-made VOIP services. The search circle eventually narrowed down to Mango Office and Telfin. Of these two, only Telfin "clings" megaphone numbers, through Multifon, to his PBX.
We connected, figured it out, set up our router, registered the settings on the Linksys SPA 504G telephone sets. In general, the connection works, the quality of the connection is good, the uptime is normal (the only time we sat without connection for two days - Telfin collapsed). Multi-channel in both directions, the queue of incoming calls, internal numbers, voice mail, hold, forwarding - all the goodies of the PBX are there and generally work fine. BUT, unpleasant moments came to light (we are talking about incoming calls to a megaphone number):

• Some of the calls come to cell phones instead of VOIP phones.
  
• Calls from hidden numbers do not go through.
  
• Tone extension dialing does not work (the megaphone has dtmf inband, the telfin rfc has something there).
  
• Incoming faxes are not getting through.
  

The last two points are a trifle, the second is unpleasant, but you can live, but the first is a problem.
We keep our cell phone on all the time. As a rule, two or three calls a day come to him. Sometimes (rarely) they went in a continuous stream to the cell, virtually paralyzing the work of consultants. We tried to set the call mode “only to Multifon” in the Multifon client - some clients reported that they could not get through to us, the connection was dropped. Therefore, the option "to the cell and to the Multifon" is left.
They sinned against telfin, corresponded for a long time, bickered, threatened to break the contract. As a result, we were allocated a specialist who took up this problem tightly. Further, according to telfin, for which I bought, for that I sell: For several days our channel “was on viewing”, I sent telfin by mail the time and numbers of calls that came to the cell. Telfin swears that nothing came to them from Megafon at that time, although registration on the megaphone server is in order. Once such a response was received from the Megafon server "SIP / 2.0 503 Service Unavailable". Telfin tried to reduce the registration time on the megaphone server - no change. It is unrealistic to get an answer from Megafon support, in response, some unsubscribes are “taking care of your problem”.
Actually, the question is: to those who have a megaphone number connected according to a similar scheme - do you have calls that come to your cell?

Answer 1

In this scheme, when calls go to both SIP and cellular, problems got out all the time, so I settled on “only SIP”

Answer 2

I connected Multifon to http://octoline.ru about 4 months ago and didn't seem to see such problems. The only thing is that the multiphone is single-channel, so when there is an incoming call, it was not possible to send an outgoing call through it. You write that multi-channel works - maybe this restriction has already been removed.