openBSC paging issue

Hi, when trying to work with multiple BTS as noted in http://umtrx.org/multi-bts-with-osmocom-and-a-single-umtrx/ , I faced a problem related to paging. When I start the BTS, I can send SMS to any connected phone but after a few minutes no SMS is sent and I can’t even make calls. I noticed that the target phone is not being paged anymore. If I restart the openBSC instance the old pending messages get sent sometimes. Also if I run the same code but with only one OSMO-BTS instance, everything works fine. I would really appreciate some help. Best regards,