OBi 100 | 110 SIP registration

I have 3 simple (I hope) questions:
1. How to configure OBi100 to send REGISTER requests every 10 min?

2. How to make it send REGISTER requests containing common "Expires: 600" filed?

3. How to make it send Keep Alive packets to keep hole in NAT/firewall opened all the registration time?


And here is some points related to each question correspondingly:
1. To send REGISTER requests every 10 min I configured OBi100 (in "Service Providers | ITSP Profile A"):
RegistrationPeriod = 1100

Why it must be 1100 instead of 600 as expected? If it's set to 1100, OBi sends its next REGISTER request in 600 sec, instead of 1100 as specified. Keep in mind that SIP server may offer a grace period (usually 1 min) over the specified by SIP client time (1100 sec in this case) to keep registration active...

Freephoneline.ca ATA Disconnect RESOLVE

The most comment support related issue at Freephoneline-Fongo is ATA voip disconnects and are related to Registration Interval.

As the owner of 13 voip ATA's and have sent many Freephoneline-Fongo support tickets. I also made many support phone calls to Freephoneline-Fongo. With the ATA; OBi, VTA-CV, Granddstream, etc) all issues have been resolved with setup changes.

It seems recently as of September 2013 all the ATA with default setting have had disconnect problems,  my question then, is Freephoneline-Fongo making changes, well I can not comment.   But I have had to re-setup all the ATA's that have been working for years until recent September 2013.   

Freephoneline.ca ATA Disconnect RESOLVE
Reason is as follows: Registration Period

The Registry expiry on the ATA needs to be setup for 3600 as per FPL guidelines:

Freephoneline.ca OBi110/202 Registration Period RESOLVE

I need your help setting up OBi110/202 with freephone settings  http://support.freephoneline.ca/entries/23120323-VoIP-Unlock-Key-Credentials. I have been using the default setting for a year without any problems. However, in the last week OBis report Register Failed: 486 Too many requests. (OBi202 concurrently runs another SIP provider without any issues.)

Required settings:
1. IP Server: voip.freephoneline.ca
2. Alternative SIP Server: voip2.freephoneline.ca
3. Transport: UDP
4. Port: 5060
5. Registration Interval: 3600 seconds (1 hour)
6. Registration Expiry: 3600 seconds (1 hour)
7. Failed Registration Re-Try Interval: 120 seconds

Please refer to OBiTALK in your answers. Variables have descriptive names and I know some of this may look obvious but please have patience.

Q1) Is there a field to enter an Alternative SIP server?