# Activation not valid - no gateways available

**URL:** <https://www.thethingsnetwork.org/forum/t/activation-not-valid-no-gateways-available/5649>\
**Category:** MultiTech Gateways\
**Created:** [February 24, 2017, 4:51pm UTC](https://www.thethingsnetwork.org/forum/t/activation-not-valid-no-gateways-available/5649 "2017-02-24T16:51:24Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![kersing](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/kersing/32/44777_2.png) [@kersing](https://www.thethingsnetwork.org/forum/u/kersing)\
**Post date:** [February 25, 2017, 11:59am UTC](https://www.thethingsnetwork.org/forum/t/activation-not-valid-no-gateways-available/5649/7 "2017-02-25T11:59:58Z")

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Hi @mark-stanley ,

> [@mark-stanley](#):
>
> I don’t think the session spans across gateways does it?

Yes it does. LoRaWAN is not WiFi where a session is bound to a particular access point, in LoRaWAN the session is bound to the back-end, so once joined every TTN gateway will handle your traffic.

> [@mark-stanley](#):
>
> Is the claim to support 3000 devices per gateway based on having total control over frequency, SF and time each device sends a message?

That claim is based on devices sending infrequently at a random frequency and a at random time. So LoRaWAN will not work for 3000 devices all sending on the hour (using a clock). It will work if those devices send at random times within an hour. (Each device can send exactly 1 hour after the last transmission as long as all devices do not send in the same timeslot)

> [@mark-stanley](#):
>
> all the devices use the same clock so the way my code currently works actively encourages collision

A simple way to avoid this is to have your code generate a random number when first started (make sure to prime the pseudo random generator with something like the current time to avoid all of the node getting the same random number [and do not start all nodes in the same second if you use the current time]) and delay all transmissions on that node that number of seconds.

Best regards,

Jac

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